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The effect of strained Si1-xGex and Si1-yCy layers for La0.75Sr0.25MnO3 films grown on oxide-buffered Si substrates.
KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
2006 (engelsk)Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 99, nr 1Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

We report the effect of strain on the structural and electrical properties of colossal magnetoresistive (CMR) La0.75Sr0.25MnO3 (LSMO) films grown on Bi4Ti3O12/CeO2/ yttrium-stabilized-zirconia-buffered Si1-xGex/Si (x=0-0.20) and Si1-yCy/Si (y=0-0.01) substrates. The strain in the buffer layer stack was tailored by varying the Ge and C contents in SiGe and SiC layers. It has been demonstrated that the relaxation of Bi4Ti3O12 layer is dependent on Ge content and this strongly affects the quality of the LSMO film. The surface roughness of LSMO was also strain dependent and samples grown on SiGe and SiC template layers were significantly smoother than that on Si. High resistivity and low values of the temperature coefficient of resistivity were obtained in LSMO films on Si0.8Ge0.2/Si and Si0.99C0.01/Si whereas Si0.9Ge0.1/Si sample shows a slight improvement in the crystalline and electrical LSMO properties compared to the CMR film grown onto the Si substrate.

sted, utgiver, år, opplag, sider
2006. Vol. 99, nr 1
Emneord [en]
thin-films, dielectric-properties, manganites
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-15374DOI: 10.1063/1.2150260ISI: 000234607200072Scopus ID: 2-s2.0-30844455355OAI: oai:DiVA.org:kth-15374DiVA, id: diva2:333415
Merknad
QC 20100525Tilgjengelig fra: 2010-08-05 Laget: 2010-08-05 Sist oppdatert: 2017-12-12bibliografisk kontrollert
Inngår i avhandling
1. Micromachined epitaxial colossal mognetoresistors for uncooled infrared bolometer
Åpne denne publikasjonen i ny fane eller vindu >>Micromachined epitaxial colossal mognetoresistors for uncooled infrared bolometer
2005 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

High quality perovskite manganites, La1-xAxMnO3 (A = Ca, Sr, Ba) are very attractive materials due to their great application potential for magnetic memory, uncooled infrared (IR) microbolometer and spintronics devices. This thesis presents studies of the growth and material characterization (including structural, electrical, magnetic and noise) of epitaxial manganite films on Si and GaAs. Furthermore, investigations about strain effect on structural and electrical properties of manganites, and finally fabrication of self-supported free standing microstructures for uncooled IR bolometer are also demonstrated.

To obtain high quality epitaxial manganite films on semiconductor substrates at room temperature, using a combination of La0.67Sr0.33MnO3 (LSMO) and La0.67Ca0.33MnO3 (LCMO) compounds, La0.67(Sr,Ca)0.33MnO3 (LSCMO) films were successfully grown on Si substrates with Bi4Ti3O12(BTO)/CeO2/YSZ buffers by pulsed laser deposition (PLD) technique. Crystallographic relations between layers shows cube-on-cube for BTO/CeO2/YSZ/Si and diagonal-on-side for LSCMO films on BTO layer. 4.4 %K-1 maximum temperature coefficient of resistivity (TCR = 1/ρ·dρ/dT) and 2.9 %kOe-1 colossal magnetoresistance (CMR) were obtained at room temperature. Assuming of a prototype of temperature sensor, 1.2 μK/√Hz of noise equivalent temperature difference (NETD) and 2.9×108 cm√Hz/W of detectivity are expected to achieve at 294 K, 30 Hz. For GaAs substrates, using MgO buffer layer, LCMO films shows 9.0 %K-1 of TCR at 223 K while LSMO exhibits 2 %K-1 at 327 K.

Systematic strain effects on structural and electrical properties of La0.75Sr0.25MnO3 LSMO) films on BTO/CeO2/YSZ-buffered Si, Si1-xGex/Si (compressive strain, x = 0.05-0.20) and Si1-yCy/Si (tensile, y = 0.01) were investigated. The strain induced from Si1-xGex/Si and Si0.99C0.01/Si has a tendency to decrease the roughness of CMR films compared to Si sample. High resistivity and low TCR values are observed for Si0.8Ge0.2/Si and Si0.99C0.01/Si samples due to excessive strains whereas Si0.9Ge0.1/Si and Si0.95Ge0.05/Si show slight improvements of films quality and TCR value.

To fabricate LSCMO manganite bolometer on Si, wet etching with KOH and BHF and dry etching methods with Ar ion beam etching (IBE) were studied. For KOH wet etching, LSCMO films show high chemical resistance with lower than 0.2 nm/min of etch rate. BHF wet etching shows high etching selectivity over photoresist mask and silicon substrates. The etch rates for LSCMO and BTO layers are 22 and 17 nm/min. For Ar IBE, LSCMO films and oxide buffer layers show similar etch rates, 16-17 nm/min that are lower compared to 24 nm/min for Si.

Free standing, self-supported heteroepitaxial LSCMO/BTO/CeO2/YSZ membranes for bolometer pixels on Si was successfully fabricated by Ar IBE and ICP etching techniques using a preannealed photoresist. The structural investigation by TEM revealed the sharp interfaces between layers. The electrical property of the free standing membrane was slightly degraded due to strain release and multi-step etching effect. These results demonstrate feasibility to use heteroepitaxial oxide structures as a thermally isolated membrane with conventional photoresist patterning.

sted, utgiver, år, opplag, sider
Stockholm: KTH, 2005. s. xvi, 78
Serie
Trita-EKT, ISSN 1650-8599 ; 2005:5
Emneord
La0.67(Sr, Ca)0.33MnO3 (LSCMO), La0.67Sr0.33MnO3 (LSMO)
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-535 (URN)
Disputas
2005-12-09, Sal C1, KTH-Electrum, 10:00
Opponent
Veileder
Merknad
QC 20101101Tilgjengelig fra: 2005-01-02 Laget: 2005-01-02 Sist oppdatert: 2010-11-01bibliografisk kontrollert

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