Deep levels generated by thermal oxidation in p-type 4H-SiC

Abstract

Thermal oxidation is an effective method to reduce deep levels, especially the Z[1∕2]-center ( Ec−0.67 eV ), which strongly suppresses carrier lifetimes in n-type 4H-SiC epilayers. The oxidation, however, simultaneously generates other deep levels, HK0 ( Ev+0.79 eV ) and HK2 ( Ev+0.98 eV ) centers, within the lower half of the bandgap of SiC, where the HK0 center is a dominant deep level with a concentration of about 1×10[13] cm[−3] after oxidation. By comparing deep levels observed in three sets of p-type 4H-SiC: oxidized, electron-irradiated, and C[+]- or Si[+]-implanted samples, we find that the HK0 and HK2 centers are complexes including carbon interstitials such as the di-carbon interstitial or di-carbon antisite. Other defects observed in p-type 4H-SiC after electron irradiation or after C[+]/Si[+] implantation are also studied.