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  • 1.
    Chen, Xi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chen, Si
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hu, Qitao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Solomon, Paul
    IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Device noise reduction for Silicon nanowire field-effect-transistor based sensors by using a Schottky junction gate2019In: ACS sensors, ISSN 2379-3694, Vol. 4, no 2, p. 427-433Article in journal (Refereed)
    Abstract [en]

    The sensitivity of metal-oxide-semiconductor field-effect transistor (MOSFET) based nanoscale sensors is ultimately limited by noise induced by carrier trapping/detrapping processes at the gate oxide/semiconductor interfaces. We have designed a Schottky junction gated silicon nanowire field-effect transistor (SiNW-SJGFET) sensor, where the Schottky junction replaces the noisy oxide/semiconductor interface. Our sensor exhibits significantly reduced noise, 2.1×10-9 V2µm2/Hz at 1 Hz, compared to reference devices with the oxide/semiconductor interface operated at both inversion and depletion modes. Further improvement can be anticipated by wrapping the nanowire by such a Schottky junction thereby eliminating all oxide/semiconductor interfaces. Hence, a combination of the low-noise SiNW-SJGFET sensor device with a sensing surface of the Nernstian response limit holds promises for future high signal-to-noise ratio sensor applications.

  • 2.
    Chen, Xi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chen, Si
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Solomon, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. IBM Thomas J. Watson Research Center.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Low-Noise Schottky Junction Trigate Silicon Nanowire Field-effect Transistor for Charge Sensing2019In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 66, no 9, p. 3994-4000Article in journal (Refereed)
    Abstract [en]

    Silicon nanowire (SiNW) field-effect transistors (SiNWFETs) are of great potential as a high-sensitivity charge sensor. The signal-to-noise ratio (SNR) of an SiNWFET sensor is ultimately limited by the intrinsic device noise generated by carrier trapping/detrapping processes at the gate oxide/silicon interface. This carrier trapping/detrapping-induced noise can be significantly reduced by replacing the noisy oxide/silicon interface with a Schottky junction gate (SJG) on the top of the SiNW. In this paper, we present a tri-SJG SiNWFET (Tri-SJGFET) with the SJG formed on both the top surface and the two sidewalls of the SiNW so as to enhance the gate control over the SiNW channel. Both experiment and simulation confirm that the additional sidewall gates in a narrow Tri-SJGFET indeed can confine the conduction path within the bulk of the SiNW channel away from the interfaces and significantly improve the immunity to the traps at the bottom buried oxide/silicon interface. Therefore, the optimal low-frequency noise performance can be achieved without the need for any substrate bias. This new gating structure holds promises for further development of robust SiNWFET-based charge sensors with low noise and low operation voltage.

  • 3.
    Chen, Xi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hu, Qitao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chen, Si
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Netzer, Nathan L.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wang, Zhenqiang
    Univ South Dakota, Dept Chem, Churchill Haines Labs, Room 115,414 East Clark St, Vermillion, SD 57069 USA.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Multiplexed analysis of molecular and elemental ions using nanowire transistor sensors2018In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 270, p. 89-96Article in journal (Refereed)
    Abstract [en]

    An integrated sensor chip with silicon nanowire ion-sensitive field-effect transistors for simultaneous and selective detection of both molecular and elemental ions in a single sample solution is demonstrated. The sensing selectivity is realized by functionalizing the sensor surface with tailor-made mixed-matrix membranes (MMM) incorporated with specific ionophores for the target ions. A biomimetic container molecule, named metal-organic supercontainer (MOSC), is selected as the ionophore for detection of methylene blue (MB+), a molecular ion, while a commercially available Na-ionophore is used for Na+, an elemental ion. The sensors show a near-Nernstian response with 56.4 ± 1.8 mV/dec down to a concentration limit of ∌1 ΌM for MB+ and 57.9 ± 0.7 mV/dec down to ∌60 ΌM for Na+, both with excellent reproducibility. Extensive control experiments on the MB+ sensor lead to identification of the critical role of the MOSC molecules in achieving a stable and reproducible potentiometric response. Moreover, the MB+-specific sensor shows remarkable selectivity against common interfering elemental ions in physiological samples, e.g., H+, Na+, and K+. Although the Na+-specific sensor is currently characterized by insufficient immunity to the interference by MB+, the root cause is identified and remedies generally applicable for hydrophobic molecular ions are discussed. River water experiments are also conducted to prove the efficacy of our sensors.

  • 4.
    Hinnemo, Malkolm
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Makaraviciute, Asta
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ahlberg, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Olsson, Jörgen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Protein sensing beyond the Debye Length Using Graphene Field-effect Transistors2018In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 18, no 16, p. 6497-6503Article in journal (Refereed)
    Abstract [en]

    Sensing biomolecules in electrolytes of high ionic strength has been a difficult challenge for field-effect transistor-based sensors. Here, we present a graphene-based transistor sensor that is capable of detection of antibodies against protein p53 in electrolytes of physiological ionic strength without dilution. As these molecules are much larger than the Debye screening length at physiological ionic strengths, this paper proves the concept of detection beyond the Debye length. The measured signal associated with the expected specific binding of the antibodies to p53 is concluded to result from resistance changes at the graphene-electrolyte interface, since a sensor responding to resistance changes rather than charge variations is not limited by Debye screening. The conclusion with changes in interface resistance as the underlying phenomena that lead to the observed signal is validated by impedance spectroscopy, which indeed shows an increase of the total impedance in proportion to the amounts of bound antibodies. This finding opens up a new route for electrical detection of large-size and even neutral biomolecules for biomedical detection applications with miniaturized sensors.

  • 5.
    Hu, Cheng
    et al.
    Fudan Univeristy.
    Gao, Xindong
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Xu, Peng
    Fudan Univeristy.
    Fu, C
    Fudan University.
    Radamson, Henrry
    KTH.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wu, Dongping
    Fudan University.
    Reactive diffusion in Ni/epi-SiGe layer stacks by microwave annealing2013Conference paper (Other academic)
  • 6.
    Hu, Qitao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chen, Si
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Solomon, Paul
    IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Effects of Substrate Bias on Low-Frequency Noise in Lateral Bipolar Transistors Fabricated on Silicon-on-Insulator Substrate2020In: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 41, no 1, p. 4-7Article in journal (Refereed)
    Abstract [en]

    This letter presents a systematic study of how the substrate bias (Vsub) modulation affects the current-voltage (I-V) characteristics and low-frequency noise (LFN) of lateral bipolar junction transistors (LBJTs) fabricated on a silicon-on-insulator(SOI) substrate. The current gain (β) of npn LBJTs at low base voltage can be greatly improved bya positive Vsub as a result of enhanced electron injection into the base near the buried oxide (BOX)/silicon interface. However, an excessive positive Vsub may also adversely affect the LFN performance by amplifying the noise generated as a result of carrier trapping and detrapping at that interface. Our results provide a practical guideline for improving both β and the overall noise performance when using our LBJT as a local signal amplifier.

  • 7.
    Hu, Qitao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chen, Xi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Norström, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zeng, Shuangshuang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Yifei, Liu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Fredrik, Gustavsson
    Swerea KIMAB, Stockholm, Sweden.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chen, Si
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Current gain and low-frequency noise of symmetriclateral bipolar junction transistors on SOI2018Conference paper (Refereed)
    Abstract [en]

    This paper presents a comprehensive study ofsymmetric lateral bipolar junction transistors (LBJTs) fabricatedon SOI substrate using a CMOS-compatible process; LBJTs findmany applications including being a local signal amplifier forsilicon-nanowire sensors. Our LBJTs are characterized by a peakgain (β) over 50 and low-frequency noise two orders ofmagnitude lower than what typically is of the SiO2/Si interfacefor a MOSFET. β is found to decrease at low base current due torecombination in the space charge region at the emitter-basejunction and at the surrounding SiO2/Si interfaces. This decreasecan be mitigated by properly biasing the substrate.

  • 8.
    Hu, Qitao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chen, Si
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Symmetric Lateral Bipolar Transistors as Low Noise Signal Amplifier2019Conference paper (Other academic)
  • 9.
    Jablonka, Lukas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Abedin, Ahmad
    Department of Electronics, KTH Royal Institute of Technology, SE-16440 Stockholm, Sweden.
    Hellström, Per-Erik
    Department of Electronics, KTH Royal Institute of Technology, SE-16440 Stockholm, Sweden.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    A novel route to a reliable extraction of the specific contact resistivity of the germanium/nickel germanide interfaceManuscript (preprint) (Other academic)
  • 10.
    Jablonka, Lukas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Gustavsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Swerea KIMAB AB, Box 7047, SE-16407 Kista, Sweden.
    Descoins, Marion
    Univ Aix Marseille, CNRS, IM2NP, Case 142, F-13397 Marseille 20, France.
    Mangelinck, Dominique
    Univ Aix Marseille, CNRS, IM2NP, Case 142, F-13397 Marseille 20, France.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Improving the morphological stability of nickel germanide by tantalum and tungsten additions2018In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, no 10, article id 103102Article in journal (Refereed)
    Abstract [en]

    To enhance the morphological stability of NiGe, a material of interest as a source drain-contact in Ge-based field effect transistors, Ta or W, is added as either an interlayer or a capping layer. The efficacy of this Ta or W addition is evaluated with pure NiGe as a reference. While interlayers increase the NiGe formation temperature, capping layers do not retard the NiGe formation. Regardless of the initial position of Ta or W, the morphological stability of NiGe against agglomeration can be improved by up to 100 °C. The improved thermal stability can be ascribed to an inhibited surface diffusion, owing to Ta or W being located on top of NiGe after annealing, as confirmed by means of transmission electron microscopy, Rutherford backscattering spectrometry, and atom probe tomography. The latter also shows a 0.3 €‰at. % solubility of Ta in NiGe at 450 °C, while no such incorporation of W is detectable.

  • 11.
    Jablonka, Lukas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Moskovkin, Pavel
    Laboratoire d'Analyse par Réactions Nucléaires (LARN), Namur Institute of Structured Matter (NISM), University of Namur (UNamur), Namur, Belgium.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Lucas, Stéphane
    Laboratoire d'Analyse par Réactions Nucléaires (LARN), Namur Institute of Structured Matter (NISM), University of Namur (UNamur), Namur, Belgium.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Metal Filling by High Power Impulse Magnetron Sputtering2019In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 52, no 36, article id 365202Article in journal (Refereed)
    Abstract [en]

    High power impulse magnetron sputtering (HiPIMS) is an emerging thin film deposition technology that provides a highly ionized flux of sputtered species. This makes HiPIMS attractive for metal filling of nanosized holes for highly scaled semiconductor devices. In this work, HiPIMS filling with Cu and Co is investigated. We show that the quality of the hole filling is determined mainly by the fraction of ions in the deposited flux and their energy. The discharge waveforms alone are insufficient to determine the ionization of the metal flux. The experimental results are in a good agreement with Monte-Carlo simulations using the measured flux characteristics. Based on the simulations, strategies to improve the filling are discussed.

  • 12.
    Johansson, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Ahlberg, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Nyberg, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Minimizing sputter-induced damage during deposition of WS2 onto graphene2017In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 110, no 9, article id 091601Article in journal (Refereed)
    Abstract [en]

    We demonstrate the sputter-deposition of WS2 onto a single-layer graphene film leaving the latter disorder-free. The sputtering process normally causes defects to the graphene lattice and adversely affects its properties. Sputtering of WS2 yields significant amounts of energetic particles, specifically negative S ions, and reflected neutral Ar, and it is therefore used as a model system in this work. The disorder-free sputtering is achieved by increasing the sputteringpressure of Ar thereby shifting the kinetic energy distribution towards lower energies for the impinging particle flux at the substrate. Raman spectroscopy is used to assess the amount of damage to the graphene film. Monte Carlo simulations of the sputteringprocess show that W is completely thermalized already at relatively low sputtering pressure, whereas Ar and S need a comparably higher pressure to thermalize so as to keep the graphene film intact. Apart from becoming completely amorphous at 2.3 mTorr, the graphene filmremains essentially disorder-free when the pressure is increased to 60 mTorr. The approach used here is generally applicable and readily extendable to sputter-deposition of other material combinations onto sensitive substrates. Moreover, it can be used without changing the geometry of an existing sputtering setup.

  • 13.
    Tseng, Chiao-Wei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wen, Chenyu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Huang, Ding-Chi
    Institute of Chemistry, Academia Sinica, Taiwan.
    Lai, Chin-Hung
    Department of Medical Applied Chemistry, Chung Shan Medical University, Taiwan.
    Chen, Si
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hu, Qitao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chen, Xi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Xu, Xingxing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Tao, Yu-Tai
    Institute of Chemistry, Academia Sinica, Taiwan.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Synergy of Ionic and Dipolar Effects by Molecular Designfor pH Sensing beyond the Nernstian Limit2019In: Advanced Science, ISSN 2198-3844Article in journal (Refereed)
  • 14.
    Wen, Chenyu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Li, Shiyu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zeng, Shuangshuang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Autogenic analyte translocation in nanopores2019In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 60, p. 503-509Article in journal (Refereed)
    Abstract [en]

    Nanopores have been widely studied for power generation and single-molecule detection. Although the power level generated by a single nanopore based on electrolyte concentration gradient is too low to be practically useful, such a power level is found sufficient to drive analyte translocation in nanopores. Here, we explore the simultaneous action of a solid-state nanopore as a nanopower generator and a nanoscale biosensor by exploiting the extremely small power generated to drive the analyte translocation in the same nanopore device. This autogenic analyte translocation is demonstrated using protein and DNA for their distinct shape, size and charge. The simple device structure allows for easy implementation of either electrical or optical readout. The obtained nanopore translocation is characterized by typical behaviors expected for an ordinary nanopore sensor powered by an external source. Extensive numerical simulation confirms the power generation and power level generated. It also reveals the fundamentals of autogenic translocation. As it requires no external power source, the sensing can be conducted with simple readout electronics and may allow for integration of high-density nanopores. Our approach demonstrated in this work may pave the way to practical high-throughput single-molecule nanopore sensing powered by the distributed energy harvested by the nanopores themselves.

  • 15.
    Wen, Chenyu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zeng, Shuangshuang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Li, Shiyu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    On rectification of ionic current in nanopores2019In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 91, no 22, p. 14597-14604Article in journal (Refereed)
  • 16.
    Wen, Chenyu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zeng, Shuangshuang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Li, Shiyu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Translocation properties of analytes through asymmetric nanopores2019Conference paper (Refereed)
  • 17.
    Wen, Chenyu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zeng, Shuangshuang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Group behavior of nanoparticles translocating multiple nanopores2018In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 90, no 22, p. 13483-13490Article in journal (Refereed)
    Abstract [en]

    Nanopores have been implemented as nanosensors for DNA sequencing, biomolecule inspection, chemical analysis, nanoparticle detection, etc. For high-throughput and parallelized measurement using nanopore arrays, individual addressability has been a crucial technological solution in order to enable scrutiny of signals generated at each and every nanopore. Here, an alternative pathway of employing arrayed nanopores to perform sensor functions is investigated by examining the group behavior of nanoparticles translocating multiple nanopores. As no individual addressability is required, fabrication of nanopore devices along with microfluidic cells and readout circuits can be greatly simplified. Experimentally, arrays of less than 10 pores are shown to be capable of analyzing translocating nanoparticles with a good signal-to-noise margin. According to theoretical predictions, more pores (than 10) per array can perform high-fidelity analysis if the noise level of the measurement system can be better controlled. More pores per array would also allow for faster measurement at lower concentration because of larger capture cross sections for target nanoparticles. By experimentally varying the number of pores, the concentration of nanoparticles, or the applied bias voltage across the nanopores, we have identified the basic characteristics of this multievent process. By characterizing average pore current and associated standard deviation during translocation and by performing physical modeling and extensive numerical simulations, we have shown the possibility of determining the size and concentration of two kinds of translocating nanoparticles over 4 orders of magnitude in concentration. Hence, we have demonstrated the potential and versatility of the multiple-nanopore approach for high-throughput nanoparticle detection.

  • 18.
    Wen, Chenyu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zeng, Shuangshuang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Signal and Noise Properties of Translocation Current in Multiple-Nanopore Sensors2019Conference paper (Refereed)
  • 19.
    Xu, Xingxing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Uppsala University.
    Makaraviciute, Asta
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Pettersson, Jean
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Considerations for the Cyclic Voltammetry of Gold in Sulfuric Acid Solutions2018Conference paper (Other academic)
    Abstract [en]

    A comprehensive understanding of the cyclic voltammetry (CV) for gold surfaces is essential for advanced applications. In the present study, a series of experiments were designed to investigate CV for gold under different experimental conditions when using a conventional configuration of a Ag/AgCl/sat. KCl reference electrode and a platinum wire counter electrode. The interferences introduced by the configuration were reflected in the three fingerprint regions of the voltammograms. It was found that the shape of the voltammograms was less reproducible at a lower sample volume when the cycle number was increased. This observation could be explained by different concentrations of Cl- leaking from the reference electrode and platinum dissolved from the counter electrode. The reproducibility of the gold oxidation and reduction (Ox/Re) region in the voltammograms was improved when gold dissolution and re-deposition caused by Cl- leakage was eliminated by using a bridge. In the hydrogen evolution and oxidation reactions (HER/HOR) region the catalytic performance of the gold electrode could be minimized by replacing the platinum counter electrode with a graphite rod. Alternatively, it could be enhanced by increasing the surface ratio of the co-deposited platinum to gold. In the electric double layer (EDL) region, peaks dependent on the concentrations of Cl- and SO42- were observed. To account for the occurrence of these peaks, a new mechanism based on the formation of neutral gold (I) complexes at very low Au+ concentrations, was proposed. 

  • 20.
    Zeng, Ruixue
    et al.
    Fudan Univ, Sch Microelect, State Key Lab ASIC & Syst, Shanghai 200433, Peoples R China..
    Zhang, Junkai
    Fudan Univ, Sch Microelect, State Key Lab ASIC & Syst, Shanghai 200433, Peoples R China..
    Sun, Cuiling
    Fudan Univ, Sch Microelect, State Key Lab ASIC & Syst, Shanghai 200433, Peoples R China..
    Xu, Ming
    Fudan Univ, Sch Microelect, State Key Lab ASIC & Syst, Shanghai 200433, Peoples R China..
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wu, Dongping
    Fudan Univ, Sch Microelect, State Key Lab ASIC & Syst, Shanghai 200433, Peoples R China..
    A reference-less semiconductor ion sensor2018In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 254, p. 102-109Article in journal (Refereed)
    Abstract [en]

    Ion sensing represents a grand research field with tremendous challenges and ample opportunities. A proper operation of ion sensors demands a robust reference electrode (RE), but on-chip integration of a conventional liquid-filled RE is incompatible with semiconductor technology for manufacturing ion-sensitive field-effect transistors as electronic sensors. Here, we demonstrate a reference-less semiconductor ion sensor, RELESIS, that integrates an interdigitated electrode (IDE) with a field-effect transistor. As a constant solution potential is no longer necessary, the use of RELESIS eliminates the need of any RE in ion sensing. The evaluated IDE comprises two intertwined metallic combs, each being covered with a specific sensing layer. One of the combs is connected to the transistor for readout while another is biased with a voltage signal source. Our extensive measurement results with pH sensing confirm that the sensitivity of RELESIS is exclusively determined by the sensitivity difference of the two sensing layers. By eliminating bulky REs, the RELESIS may find myriad ion-sensing applications owing to its miniaturisability, integrability, flexibility and cost advantages.

  • 21. Zeng, Ruixue
    et al.
    Zhang, Junkai
    Yang, Hui
    Sun, Cuiling
    Xu, Ming
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wu, Dongping
    Modelling and Characterization of Novel Reference-Less Semiconductor Ion Sensor for pH Sensing2019In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 281, p. 60-71Article in journal (Refereed)
    Abstract [en]

    A SPICE macromodel is developed for a novel reference-less semiconductor ion sensor (RELESIS), which has been proposed to eliminate the use of reference electrode in the field effect based sensor detection. The working principle of the RELESIS, previously validated by a prototype device via pH sensing, is featured by non-constant bulk solution potential, which distincts itself from any conventional ion sensitive field effect transistor. Simulations are performed here using the macromodel and the results fit well with the experimental data. The proposed SPICE macromodel can be used to predict the behavior of the RELESIS and carry out performance optimizations for the RELESIS to be used in various applications.

  • 22.
    Zeng, Shuangshuang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    A nanopore array of individual addressability enabled by integrating microfluidics and a multiplexer2019In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 20, no 3, p. 1558-1563Article in journal (Refereed)
    Abstract [en]

    Solid-state nanopores (SSN) are of significant potential as a versatile tool for chemical sensing, biomolecule inspection, nanoparticle detection, etc. High throughput characterization of SSN in an arrayed format is highly desired for a wide range of applications. Herein, we demonstrate a novel design to integrate an SSN array with microfluidics and a multiplexer. Ionic current measurement on each nanopore can then be individually addressed fluidically and/or electrically with minimum cross talk (electric leakage). This integration provides a scalable platform for automated high-throughput, low-cost, and rapid electrical characterization potentially of a large number of SSN.

  • 23.
    Zeng, Shuangshuang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Uppsala University.
    Li, Shiyu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Utterström, Johanna
    Linköping University.
    Wen, Chenyu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Selegård, Robert
    Linköping University.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Aili, Daniel
    Linköping University.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Mechanism and kinetics of lipid bilayer formation in solid-state nanopores2020In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827Article in journal (Refereed)
    Abstract [en]

    Solid-state nanopores provide a highly versatile platform for rapid electrical detection and analysis of single molecules. Lipid bilayer coating of the nanopores can reduce non-specific analyte adsorption to the nanopore sidewalls and increase the sensing selectivity by providing possibilities for tethering specific ligands in a cell-membrane mimicking environment. However, mechanism and kinetics of lipid bilayer formation from vesicles remain unclear in the presence of nanopores. In this work, we used a silicon-based, truncated-pyramidal nanopore array as the support for lipid bilayer formation. Lipid bilayer formation in the nanopores was monitored in real-time by the change in ionic current through the nanopores. Statistical analysis revealed that a lipid bilayer is formed from instantaneous rupture of individual vesicle upon adsorption in the nanopores, differing from the generally agreed mechanism that lipid bilayers form at a high vesicle surface coverage on a planar support. The2dependence of the lipid-bilayer formation process as a function of applied bias, vesicle size and concentration was systematically studied. In addition, the non-fouling properties of the lipid bilayer coated nanopores were demonstrated during long single stranded DNA translocation through the nanopore array. The findings indicate that lipid bilayer formation process can be modulated by introducing nanocavities intentionally on the planar surface to create active sites or changing the vesicle size and concentration.

  • 24.
    Zeng, Shuangshuang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wen, Chenyu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Li, Shiyu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chen, Xi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chen, Si
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Controlled size reduction and its underlying mechanism to form solid-state nanopores via electron beam induced carbon deposition2019In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 30, no 45, article id 455303Article in journal (Refereed)
    Abstract [en]

    Solid-state nanopores have drawn considerable attention for their potential applications in DNA sequencing and nanoparticle analysis. However, fabrication of nanopores, especially those of diameter below 30 nm, requires sophisticated techniques. Here, a versatile method to controllably reduce the diameter of prefabricated large-size pores down to sub-30 nm without greatly increasing the effective pore depth from the original membrane thickness is shown. This method exploits carbon deposition achieved via hydrocarbon evaporation, induced by an incident beam of electrons, and subsequent dissociation of hydrocarbon to solid carbon deposits. The carbon deposition employs a conventional scanning electron microscope equipped with direct visual feedback, along with a stable hydrocarbon source nearby the sample. This work systematically studies how electron beam accelerating voltage, imaging magnification, initial pore size and membrane composition affect the process of pore size reduction. Secondary electrons generated in the membrane material are confirmed to be the main cause of the dissociation of hydrocarbon. Thicker carbon deposited on one side than on the other of the membrane results in an asymmetric nanopore shape and a rectifying ionic transport. A physico-phenomenological model combined with Monte Carlo simulations is proposed to account for the observed carbon deposition behaviors.

  • 25.
    Zeng, Shuangshuang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wen, Chenyu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Solomon, Paul
    IBM TJ Watson Res Ctr, Yorktown Hts, NY USA.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Rectification of protein translocation in truncated-pyramidal nanopores2019In: Nature Nanotechnology, ISSN 1748-3387, E-ISSN 1748-3395, Vol. 14, p. 1056-1062Article in journal (Refereed)
    Abstract [en]

    Solid-state nanopore technology presents an emerging single-molecule-based analytical tool for the separation and analysis of nanoparticles. Different approaches have been pursued to attain the anticipated detection performance. Here, we report the rectification behaviour of protein translocation through silicon-based truncated pyramidal nanopores. When the size of translocating proteins is comparable to the smallest physical constriction of the nanopore, the frequency of translocation events observed is lower for proteins that travel from the larger to the small opening of the nanopore than for those that travel in the reverse direction. When the proteins are appreciably smaller than the nanopore, an opposite rectification in the frequency of translocation events is evident. The maximum rectification factor achieved is around ten. Numerical simulations reveal the formation of an electro-osmotic vortex in such asymmetric nanopores. The vortex–protein interaction is found to play a decisive role in rectifying the translocation in terms of polarity and amplitude. The reported phenomenon can be potentially exploitable for the discrimination of various nanoparticles.

  • 26.
    Zeng, Shuangshuang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wen, Chenyu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Single molecule detection via solid state carbon nanopore2018Conference paper (Other academic)
    Abstract [en]

    Single molecule detection is of vital importance for fundamental biotechnology research and practical applications. Among the numerous single molecule detection techniques, solid-state nanopores have been developed as single molecule sensors for the investigation of unlabeled biopolymers such as DNA, RNA and protein owing to their robustness, pore size controllability and tunability of physical/chemical properties. The most commonly used method today to form ultra-small nanopores relies on using focused high energy electron beams on a transmission electron microscope (TEM). However, the sophisticated operation of TEM, high cost and low throughput limit its extensive applications. In this work, we start with electron beam lithography combined with reactive ion etching to massively prefabricate nanopores with relatively large size in free-standing silicon nitride membranes. Then, electron beam irradiation is used to deposit carbon with a conventional scanning electron microscope so as to reduce the size of prefabricated pores. This process leads to the controllable formation of solid-state carbon nanopores sub-30 nm in diameter. We subsequently use the carbon nanopores to study translocation of λ-DNA as a demonstration of the capability of such carbon nanopores. By tuning bias voltage, the translocation events show regular changes in amplitude, dwell time and appearance frequency. With this advanced nanopore platform, detection of single DNA molecules is achieved with a high signal-to-noise ratio of ~6.

  • 27.
    Zhang, Da
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Solomon, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Low-frequency noise originating from the dynamic hydrogen ion reactivity at the solid/liquid interface of ion sensors2018Conference paper (Refereed)
    Abstract [en]

    Low-frequency noise (LFN) is of significant implications in ion sensing. As a primary component of LFN for ion sensing in electrolytes, the solid/liquid interfacial noise remains poorly explored especially regarding its relation to the surface binding/de-binding dynamic properties. In this talk, the solid/liquid interfacial noise will first be characterized by direct electrical measurements. It will then be correlated to the dynamic properties of surface protonation (i.e., hydrogen binding) and deprotonation (i.e., hydrogen de-binding) processes using an impedance spectroscopy. Finally we will provide insights into how detailed surface properties may affect the noise performance of an ion sensor operating in electrolytes.

  • 28.
    Zhang, Youwei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wang, Jiao
    Wang, Bing
    Shao, Jinhai
    Deng, Jianan
    Cong, Chunxiao
    Hu, Laigui
    Tian, Pengfei
    Liu, Ran
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Qiu, Zhi-Jun
    Extending the Spectral Responsivity of MoS2 Phototransistors by Incorporating Up-Conversion Microcrystals2018In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 6, no 21, article id 1800660Article in journal (Refereed)
    Abstract [en]

    Layered 2D semiconductors are characterized by unique photoelectric properties and, therefore, constitute a new class of basic building block for next‐generation optoelectronics. However, their wide bandgaps limit the spectral responsivity to a narrow range. Here, a facile approach is demonstrated by integrating β‐NaYF4:Yb3+, Er3+ up‐conversion microcrystals (UCMCs) with monolayer‐MoS2 phototransistors to break this bandgap‐imposed barrier and to drastically extend the responsivity range. In essence, the UCMCs up‐convert a near‐infrared excitation at 980 nm to visible light of photons with energy matching the large bandgap (i.e., 1.8 eV) of monolayer‐MoS2, thereby activating the phototransistor with remarkable photocurrent and minimum interference. This approach leads to preservation of the excellent electrical merits of monolayer‐MoS2 and simultaneous retention of its low dark current and high photoresponsivity to the above‐bandgap lights. Significantly, an enhancement by over 1000 times is achieved for both responsivity and specific detectivity at 980 nm excitation. Moreover, the rate of response is kept identical to that when the MoS2 phototransistor is excited by a visible light. Therefore, integrating with UCMCs can enable the emerging 2D semiconductors of wide bandgap to respond to infrared excitations with high efficacy and without sacrificing their performance in the visible region.

  • 29.
    Zhang, Youwei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Fudan Univ, Sch Informat Sci & Technol, State Key Lab ASIC & Syst, Shanghai 200433, Peoples R China.
    Zheng, Hemei
    Fudan Univ, Sch Informat Sci & Technol, State Key Lab ASIC & Syst, Shanghai 200433, Peoples R China.
    Wang, Qiyuan
    Fudan Univ, Sch Informat Sci & Technol, State Key Lab ASIC & Syst, Shanghai 200433, Peoples R China.
    Cong, Chunxiao
    Fudan Univ, Sch Informat Sci & Technol, State Key Lab ASIC & Syst, Shanghai 200433, Peoples R China.
    Hu, Laigui
    Fudan Univ, Sch Informat Sci & Technol, State Key Lab ASIC & Syst, Shanghai 200433, Peoples R China.
    Tian, Pengfei
    Fudan Univ, Sch Informat Sci & Technol, State Key Lab ASIC & Syst, Shanghai 200433, Peoples R China.
    Liu, Ran
    Fudan Univ, Sch Informat Sci & Technol, State Key Lab ASIC & Syst, Shanghai 200433, Peoples R China.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Qiu, Zhi-Jun
    Fudan Univ, Sch Informat Sci & Technol, State Key Lab ASIC & Syst, Shanghai 200433, Peoples R China.
    Competing Mechanisms for Photocurrent Induced at the Monolayer-Multilayer Graphene Junction2018In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 14, no 24, article id 1800691Article in journal (Refereed)
    Abstract [en]

    Graphene is characterized by demonstrated unique properties for potential novel applications in photodetection operated in the frequency range from ultraviolet to terahertz. To date, detailed work on identifying the origin of photoresponse in graphene is still ongoing. Here, scanning photocurrent microscopy to explore the nature of photocurrent generated at the monolayer-multilayer graphene junction is employed. It is found that the contributing photocurrent mechanism relies on the mismatch of the Dirac points between the monolayer and multilayer graphene. For overlapping Dirac points, only photothermoelectric effect (PTE) is observed at the junction. When they do not coincide, a different photocurrent due to photovoltaic effect (PVE) appears and becomes more pronounced with larger separation of the Dirac points. While only PTE is reported for a monolayer-bilayer graphene junction in the literature, this work confirms the coexistence of PTE and PVE, thereby extending the understanding of photocurrent in graphene-based heterojunctions.

  • 30.
    Zhao, Jie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sun, Rui
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Wen, Chenyu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wu, Biao
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    High-Conductivity Reduced-Graphene-Oxide/Copper Aerogel for Energy Storage2019In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 60, p. 760-767Article in journal (Refereed)
    Abstract [en]

    This work reports a room-temperature, solution-phase and one-pot method for macro-assembly of a three-dimensional (3D) reduced-graphene-oxide/copper hybrid hydrogel. The hydrogel is subsequently transformed into a highly conductive aerogel via freeze-drying. The aerogel, featuring reduced graphene oxide (rGO) networks decorated with Cu and CuxO nanoparticles (Cu/CuxO@rGO), exhibits a specific surface area of 48 m(2)/g and an apparent electrical conductivity of similar to 33 and similar to 430 S/m prior to and after mechanical compression, respectively. The compressed Cu/CuxO@rGO aerogel delivers a specific capacity of similar to 453 mAh g(-1) at a current density of 1 A/g and similar to 184 mAh g(-1) at 50 A/g in a 3 M KOH aqueous electrolyte evidenced by electrochemical measurements. Galvanostatic cycling tests at 5 A/g demonstrates that the Cu/CuxO@rGO aerogel retains 38% (similar to 129 mAh g(-1)) of the initial capacity (similar to 339 mAh g(-1)) after 500 cycles. The straightforward manufacturing process and the promising electrochemical performances make the Cu/CuxO@rGO aerogel an attractive electrode candidate in energy storage applications.

  • 31.
    Zhao, Jie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Northwest Univ, Coll Chem & Mat Sci, Minist Educ, Key Lab Synthet & Nat Funct Mol Chem, Xian, Shaanxi, Peoples R China.
    Wen, Chenyu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Sun, Rui
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wu, Biao
    Northwest Univ, Coll Chem & Mat Sci, Minist Educ, Key Lab Synthet & Nat Funct Mol Chem, Xian, Shaanxi, Peoples R China.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    A Sequential Process of Graphene Exfoliation and Site-Selective Copper/Graphene Metallization Enabled by Multifunctional 1-Pyrenebutyric Acid Tetrabutylammonium Salt2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 6, p. 6448-6455Article in journal (Refereed)
    Abstract [en]

    This paper reports a procedure leading to shear exfoliation of pristine few-layer graphene flakes in water and subsequent site-selective formation of Cu/graphene films on polymer substrates, both of which are enabled by employing the water soluble 1-pyrenebutyric acid tetrabutylammonium salt (PyB-TBA). The exfoliation with PyB-TBA as an enhancer leads to as-deposited graphene films dried at 90 °C that are characterized by electrical conductivity of ∼110 S/m. Owing to the good affinity of the tetrabutylammonium cations to the catalyst PdCl42–, electroless copper deposition selectively in the graphene films is initiated, resulting in a self-aligned formation of highly conductive Cu/graphene films at room temperature. The excellent solution-phase and low-temperature processability, self-aligned copper growth, and high electrical conductivity of the Cu/graphene films have permitted fabrication of several electronic circuits on plastic foils, thereby indicating their great potential in compliant, flexible, and printed electronics.

  • 32.
    Zou, Haiyang
    et al.
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Li, Xiaogan
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Dai, Guozhang
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA;Cent S Univ, Sch Phys & Elect, Hunan Key Lab Super Microstruct & Ultrafast Proc, Changsha 410083, Hunan, Peoples R China.
    Peng, Wenbo
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Ding, Yong
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Zhang, Ying
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Wang, Aurelia Chi
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Zhang, Steven L.
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
    Xu, Cheng
    Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA;China Univ Min & Technol, Sch Mat Sci & Engn, Xuzhou 221116, Jiangsu, Peoples R China.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wang, Zhong Lin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA;Chinese Acad Sci, Beijing Inst Nanoenergy & Nanosyst, Beijing 100083, Peoples R China.
    Dramatically Enhanced Broadband Photodetection by Dual Inversion Layers and Fowler-Nordheim Tunneling2019In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 13, no 2, p. 2289-2297Article in journal (Refereed)
    Abstract [en]

    Silicon photonics is now widely accepted as a key technology in a variety of systems. But owing to material limitations, now it is challenging to greatly improve the performance after decades of development. Here, we show a high-performance broadband photodetector with significantly enhanced sensitivity and responsivity operating over a wide wavelength range of light from near-ultraviolet to near-infrared at low power consumption. The specially designed textured top ceiling electrode works effectively as an antireflection layer to greatly improve the absorption of near-infrared light, thereby overcoming the absorption limitation of near-infrared light. Instead of the conventional p-n junction and p-intrinsic-n junction, we introduce a similar to 15 nm thick alumina insulator layer between a p-type Si substrate and n-type ZnO nanowire (NW) arrays, which significantly enhances the charge carrier separation and collection efficiency. The photosensing responsivity and sensitivity are found to be nearly 1 order of magnitude higher than that of a reference device of p-Si/n-ZnO NW arrays, significantly higher than the commercial silicon photodiodes as well. The light-induced charge carriers flow across the appropriate thickness of insulator layer via the quantum mechanical Fowler-Nordheim tunneling mechanism. By virtue of the piezo-phototronic effect, the charge density at the interfaces can be tuned to alter the energy bands and the potential barrier distance for tunneling. Additionally, along with the use of incident light of different wavelengths, the influence of the insulator layer on the transport of electrons and holes separately is further investigated. The demonstrated concepts and study would lead to sensitivity improvement, quality enhancement of data transfer, decrease of power consumption, and cost reduction of silicon photonics.

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