作者:
SK Lee，CM Zetterling，M Östling，JP Palmquist，H Högberg
关键词:
4H-SiC；Contact resistivity；Epitaxial titanium carbide；Ohmic contacts
摘要:
Low resistivity Ohmic contacts of epitaxial titanium carbide to highly doped n- (1.3x10cm) and p-(>10cm) type epilayer on 4H-SiC were investigated. The titanium carbide contacts were epitaxially grown using co-evaporation with an e-beam for Ti and a Knudsen cell for Cin a UHV system. A comparison of epitaxial evaporated Ti Ohmic contacts on pepilayer of 4H-SiC is also given. The as-deposited TiC Ohmic contacts showed a good Ohmic behavior and the lowest contact resistivity ( ) was 7.4x10惟cmat 200C for n-type, and 1.1x10惟cmat 25C for p-type contacts. Annealing at 950C did not improve the Ohmic contact to n-type 4H-SiC, but instead resulted in an increase in to 4.01x10惟cmat 25C. In contrast to n-type, after annealing at 950C the specific for p-type SiC reached its lowest value of 1.9x10惟cmat 300C. Our results indicate that co-evaporated TiC contacts to n- and p-type epilayers of 4H-SiC should not require a higher post-annealing temperature, contrary to earlier works. Material characteristics, utilizing X-ray diffraction, Low energy electron diffraction, Rutherford backscattering spectrometry, transmission electron microscopy, and X-ray photoelectron spectroscopy measurements are also discussed.
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