Fabrication of mesa-type pn diodes without forward degradation on ultara-high-quality 6H-SiC substrate

摘要

Using our own substrate growth and epitaxial growth techniques, we fabricated a 1.4 kV mesa-type 6H-SiC pn diode with an ideal avalanche breakdown and without forward degradation. The 6H-SiC substrates were grown on Lely crystals with no micropipes and only minimal defects. A pn junction was fabricated by chemical vapor deposition (CVD) with p~+~- epitaxial films. We obtained 1.4 kV breakdown voltage, consistent with the ideal breakdown voltage calculated from the thickness (10μm) and doping concentration (2xl0~(16)cm~(-3)) of the drift layer. The application of 200 A/cm~2 current stress in the forward direction produced no degradation, which is often observed with pn diodes on normal commercial substrates.