Extended Defects in SiC: Selective Etching and Raman Study

Abstract

Controlling the electrical properties of SiC requires knowledge of the nature and properties of extended defects. We have employed orthodox defect-selective etching and photo-etching methods to reveal typical and new structural defects in commercial SiC wafers. For photo-etching, the etch rate increases as the free carrier concentration decreases. The etch rate can be used to estimate the free carrier concentration with higher precision, and over a larger lateral and depth range than that accessed by Raman scattering. The logarithmic dependence of the etch rate on the free carrier concentration has been characterized.

Effect of TCS gas flow and pre-etching on homopitaxial growth of 4H-SiC

“… 35 When the pre-etching temperature is not sufficiently high or the pre-etching time is insufficient, inadequate etching may occur, resulting in the incomplete removal of defects such as scratches on the substrate surface, thereby affecting the substrate's quality. 36,37 More importantly, the substrate surface steps may not be fully exposed, thereby affecting the subsequent step-flow growth process. Conversely, if the pre-etching time is too long, over-etching may occur.…”