TEMPERATURE-DEPENDENCE OF AVALANCHE BREAKDOWN FOR EPITAXIAL DIODES IN4H SILICON-CARBIDE

The temperature dependence of avalanche breakdown is investigated for uniform and microplasma-related breakdown in epitaxial 4H SiC p-n junc tions. P-n mesa diodes fabricated with positive angle beveling and oxi de passivation can withstand temperatures of up to 300-400 degrees C i n the breakdown regime. Uniform avalanche breakdown in 4H silicon carb ide appears to have a positive temperature coefficient, in contrast to the 6H polytype, where the temperature coefficient is negative. The i nfluence of deep levels on avalanche breakdown in epitaxial diodes is of minor importance for uniform breakdown, but appears to be significa nt for breakdown through microplasmas. A negative temperature coeffici ent for the avalanche breakdown voltage can be observed even for 4H Si C if the breakdown is dominated by microplasmas. (C) 1998 American Ins titute of Physics. [S0003-6951(98)01739-2].