Characterization of Thermally Oxidized SiO2/SiC Interfaces by Leakage Current under High Electric Field, Cathode Luminescence (CL), X-Ray Photoelectron Spectroscopy (XPS) and High-Resolution Rutherford Backscattering Spectroscopy (HR-RBS)

Wet and N2O oxidized SiO2/SiC for C-face substrates were comprehensively investigated to clarify the origin of oxide defects which affect channel mobility and threshold voltage stability by using leakage-current analysis. The estimated defects are identified by cathode luminescence, X-ray photoelectron spectroscopy, and high-resolution Rutherford backscattering spectroscopy. The origin of the observed oxide defects might be complex defect of O vacancy defects and/or C related defects including N.

Effects of N-Face Finishing on Geometry of Double-Side Polished GaN Substrate

Difficulties involved in producing Double-Side Polished (DSP) GaN substrate are extracted and approaches to overcoming them are reported in this paper. Mechanical polishing with a neutral diamond slurry of pH 7.0 for the N-face and CMP for the Ga-face are widely applied to obtain DSP GaN substrates. Accordingly, the substrate exhibits transparency. However, this is accompanied by approximately 100 µm of bowing due to the Twyman effect. In this paper, the reduction of the substrate bowing to 10 µm is successfully achieved through the use of an acidic diamond slurry with a pH of 1.8 instead of a neutral slurry. Cathode luminescence reveals that an acidic diamond slurry also induces less subsurface damage in the N-face than does the neutral one. We conclude that the stress on the N-face induced by the subsurface damage in the case of polishing with an acidic diamond slurry comes closer to that of the Gaface finished via CMP.