Characterization of Ti/Al Ohmic Contacts to p-Type 4H-SiC Using Cathodoluminescence and Auger Electron Spectroscopies
We have used depth-resolved cathodoluminescence and Auger electron spectroscopies, DRCLS and AES, respectively, to probe the electronic structure and the composition of Ti/Al ohmic contacts to p-type SiC on a nanometer scale. A continuous Ti-Si-C compound layer was observed using the Auger depth profile. No interfacial Al segregation was found. The secondary electron threshold technique showed a continuous decrease in work function from the p-type SiC to the Ti-Si-C compound layer. Our results support an ohmic contact mechanism by an intermediate semiconductor layer which reduces the otherwise large interfacial Schottky barrier height. DRCLS revealed a ~2.78 eV sub-band gap transition enhanced by interfacial reaction in the near-interface SiC, suggesting the formation of additional C or Si vacancies.
Robert P. Devaty, David J. Larkin and Stephen E. Saddow
M. Gao et al., "Characterization of Ti/Al Ohmic Contacts to p-Type 4H-SiC Using Cathodoluminescence and Auger Electron Spectroscopies", Materials Science Forum, Vols. 527-529, pp. 891-894, 2006