Transistors with Barium Passivation*

We report on electrically detected magnetic resonance measurements on 4H-SiC/SiO₂ metal oxide semiconductor field effect transistors. 4H-SiC/SiO₂ based MOSFETs show great promise for high power and high temperature applications. However, the SiC/SiO₂ interface has a high concentration of interface and near-interface traps which limits effective channel mobility. Passivation decreases the interface state density and thus increases the mobility. Passivation schemes typically including post-oxidation annealing in NO. Recent work suggests promise for a barium interfacial layer (IL) before oxidation¹. We probe the atomic scale defects at the SiC/SiO₂ in NO and barium treated devices and compare the results with those on unpassivated devices. Both the NO anneal and the barium IL greatly reduce the density of near-interface silicon vacancies, but yield somewhat different post-passivation defect structures.

¹ D.J. Lichtenwalner, L. Cheng, S. Dhar, A. Agarwal, and J.W. Palmour, Appl. Phys. Lett. 105, 1 (2014).