High voltage 6H-SiC rectifiers: prospects and progress

Summary form only given. There are several crucial device fabrication issues that must be solved before truly advantageous SiC power devices can be realized experimentally. Progress in the fabrication of experimental high-voltage epitaxial pn and Schottky junction 6H-SiC diodes is reported. Doping concentrations in 6H-SiC epilayers grown by atmospheric-pressure chemical vapor deposition have been reduced, making possible the fabrication of 2000-V silicon carbide diode rectifiers ever reported. A 24-μm-thick 2×10¹⁵ cm^-3 n-type epilayer was the key to the 600-V improvement in reported 6H-SiC blocking voltage in the p⁺n mesa-structure diodes. The devices on this wafer were small enough (areas ⩽4×10^-4 cm²) that a 2000-V functional yield in excess of 50% was obtained. Larger-area (1 mm²) pn junction devices exhibited point failures that prevented high-voltage yields above 20%. An investigation into the failure mechanism of the larger-area pn diodes, which typically failed at reverse voltages between 100 V and 400 V, was conducted. In at least half of all the defective diodes, it was found that the points of failure corresponded to micropipe defects in the 6H-SiC