CHARACTERIZATION OF SILICON-CARBIDE SURFACES OF 6H-POLYTYPE, 15R-POLYTYPE AND 3C-POLYTYPE BY OPTICAL 2ND-HARMONIC GENERATION IN COMPARISON WITH X-RAY-DIFFRACTION TECHNIQUES

Second-harmonic (SH) generation is a versatile method applicable to in -situ characterization of even noncentrosymmetric media like silicon c arbide (SiC). In particular, the azimuthal rotational anisotropy of th e SH response from SiC observed in reflection allows identification of various polytypes. The nonlinear-optical results are compared to X-ra y diffraction data. The abundance of information obtained through the SH studies makes characteristic finger printing of the 6H, 15R, and 3C polytypes of SiC is possible. The spatial resolution of the optical s ampling was about 50 mu m in the lateral direction with a typical pene tration depth of 100 nm for the fundamental radiation. Defect regions of different crystallographic structures in large SIC samples were ide ntified by observing the spatially resolved dependence of the SH inten sity.