Ultrahigh-Voltage SiC p-i-n Diodes With Improved Forward Characteristics

Silicon carbide (SiC) p-i-n diodes having five different n^--layer (i-layer) thicknesses from 48 to 268 μm are fabricated. The forward characteristics of SiC p-i-n diodes are significantly improved by carrier-lifetime enhancement. After this improvement, the differential on-resistance is inversely proportional to the square root of current density for all the diodes with different thicknesses of n^--layer. As a result, the forward current density-voltage characteristics can be approximately expressed by a parabolic function, as in the case of Si p-i-n diodes. Using a 268-μm-thick n^--layer, the lifetime enhancement, and an improved space-modulated junction termination extension structure, a very high blocking voltage over 26.9 kV and low differential on-resistance of 9.7 mΩ·cm² are achieved.