Generation of deep levels near the 4H-SiC surface by thermal oxidation

Deep levels near the surface of 4H-SiC after dry oxidation were investigated. A large and broad peak appeared in the low-temperature range of deep level transient spectroscopy (DLTS) spectra after oxidation of SiC at 1300oC, indicating multiple deep levels energetically located near the conduction band edge are generated inside SiC by thermal oxidation. Analyses of the DLTS spectra acquired with changing the bias voltage revealed that the majority of deep levels is located very near the SiC surface, within about 6 nm-deep region from the surface. The area density of the observed deep levels is higher than 3×1012 cm-2.