Diamond-SiC Heterojunctions - the influence of methane ratio on the electrical behavior of CVD diamond

Abstract

Due to the properties of wide band gap materials, diamond / SiC heterojunctions are well-suited for high power / high temperature applications. Such devices can be fabricated by depositing p-type boron-doped diamond (BDD) films on n-type SiC substrates using hot filament chemical vapour deposition (HFCVD). The behaviour of the heterojunction depends on the properties of the diamond films and, as such, the fabrication of efficient devices requires previous knowledge of the impact the deposition conditions (such as gas concentration, substrate temperature and pressure). have on the morphology and electrical properties of the diamond film. Characteristics such as crystallite orientation and size, for instance, determine the concentration of boron doping which in turn affects the resistivity of the films (which lowers as the boron concentration increases). In order to calibrate the HFCVD system used in this work, diamond films were deposited using different experimental conditions; the films were characterised for morphological differences and differences in quality using SEM imaging and Raman spectroscopy. The effect of these parameters on the resistivity of the films was also studied.