Fabrication of active devices using semiconducting SiC for use in heavy environment

点击翻译按钮获取中文摘要

Fundamental studies on fabrication of active devices have been carried out using semiconducting 3C-SiC for use in heavy environment. The crystal growth conditions were made clear to obtain the flat surface which is strongly required for device fabrication. And, a precise processing of 3C-SiC was developed. Using the above results, simple devices such as MOS, Schottky and pn junctions were prepared. As an active device, MES FET was designed and the electrical characteristics were simulated. Some samples were fabricated. The following results were obtained.(1) Flatness of grown layers: Different orientations ((100),(110),(111)) were examined for the epitaxial growth. Single crystals of 3C-SiC with a large area of 2 inch diameter was obtained. By observing anti-phase domains which cause rough surfaces, a new method to get rid of surface roughness was developed.(2) Precise processing: Plasma etching technology for 3C-SiC was established using <CF_4> and <O_2> gases. The etch rate can be controlled by the content of <O_2> gas. Chromium metal was found to be usable as an etching mask.(3) Preparation of Diodes: Diodes of MOS, Schottky and ph-junction types using 3C-SiC were prepared and the electrical characteristics were measured. Inversion in 3C-SiC MOS diodes under illumination was obtained for the first time.(4) Design and Fabrication of MES FET: Device structures of MES FET using 3CSiC single crystals were designed and the electrical characteristics were simulated. MES FETs were fabricated using Schottky gates on the 3C-SiC layers which were epitaxially grown on high resistive p-type 3C-SiC obtained by doping <B_2> <H_6> . Although Schottky characteristics of the device were enough good, operation of a FET was not obtained due to insufficient ohmic characteristics at source and drain electrodes.