Electron paramagnetic resonance and theoretical studies of Nb in 4H- and 6H-SiC
2012 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 112, no 8, 083711- p.Article in journal (Refereed) Published
High purity silicon carbide (SiC) materials are of interest from high-power high temperature applications across recent photo-voltaic cells to hosting solid state quantum bits, where the tight control of electrically, optically, and magnetically active point defects is pivotal in these areas. 4H- and 6H-SiC substrates are grown at high temperatures and the incorporation of transition metal impurities is common. In unintentionally Nb-doped 4H- and 6H-SiC substrates grown by high-temperature chemical vapor deposition, an electron paramagnetic resonance (EPR) spectrum with C-1h symmetry and a clear hyperfine (hf) structure consisting of ten equal intensity hf lines was observed. The hf structure can be identified as due to the interaction between the electron spin S - 1/2 and the nuclear spin of Nb-93. Additional hf structures due to the interaction with three Si neighbors were also detected. In 4H-SiC, a considerable spin density of similar to 37.4% was found on three Si neighbors, suggesting the defect to be a complex between Nb and a nearby carbon vacancy (V-C). Calculations of the Nb-93 and Si-29 hf constants of the neutral Nb on Si site, Nb-Si(0), and the Nb-vacancy defect, NbSiVC0, support previous reported results that Nb preferentially forms an asymmetric split-vacancy (ASV) defect. In both 4H- and 6H-SiC, only one Nb-related EPR spectrum has been observed, supporting the prediction from calculations that the hexagonal-hexagonal defect configuration of the ASV complex is more stable than others.
Place, publisher, year, edition, pages
American Institute of Physics (AIP) , 2012. Vol. 112, no 8, 083711- p.
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-86385DOI: 10.1063/1.4759362ISI: 000310597500056OAI: oai:DiVA.org:liu-86385DiVA: diva2:576872
Funding Agencies|Swedish Energy Agency||Swedish Research Council VR/Linne Environment LiLI-NFM, FP7|270197|NHDP|TAMOP-4.2.1/B-09/1/KMR-2010-0002|Swedish National Infrastructure for Computing||Knut and Alice Wallenberg Foundation||2012-12-142012-12-142015-05-12