Control of carrier lifetime of thick n-type 4H-SiC epilayers by high-temperature Ar annealing

We investigated the carrier lifetime and Z1/2 center density of thick n-type 4H-SiC epilayers, which were oxidized and subsequently annealed in Ar at high temperatures. The Z1/2 center density decreased below the detection limit in the region to, at least, a 130 µm depth by thermal oxidation. After subsequent high-temperature annealing, the Z1/2 center density increased with increasing annealing temperature, while the distribution of the Z1/2 center density was nearly uniform to a 130 µm depth. The carrier lifetime could be controlled from 26 to 2.4 µs by changing the annealing temperature from 1600 to 1800 °C.