Ge Assisted SiC Epitaxial Growth by CVD on SiC Substrate

Abstract

This paper presents the results obtained after chemical vapor deposition of SiC with the addition of GeH4gas to the classical SiH4+C3H8precursor system. Epitaxial growth was performed either on 8°off-axis or on-axis 4H-SiC substrate in the temperature range 1500-1600°C. In the off-axis case, the layer quality (surface morphology and defect density) does not change though accompanied with Ge droplets accumulation at the surface. The Ge incorporation level was found to increase with temperature in the 10171018cm-3ranges. It was observed that adding GeH4leads to the increase of the n type doping level by a factor from 2 to 5 depending on the C/Si ratio. In the on-axis case, GeH4was only added to the gas phase before starting the SiC growth. It was found that there is a conditions window (temperature and GeH4flux) for which 3C-SiC twin free layers can be grown. Adding this foreign element before SiC growth clearly modifies SiC nucleation on on-axis substrate.