Very high epitaxial growth rate of SiC using MTS as chloride-based precursor

Abstract

We present results on chloride-based homoepitaxial growth of 4H-SiC in a hot wall CVD reactor. The addition of chlorinated species to the gas mixture prevents silicon nucleation in the gas phase, thus allowing higher input flows of the precursors resulting in much higher growth rate than that of standard SiC epitaxial growth using only silane, SiH 4, and ethylene, C 2H 4, as precursors. We have achieved growth rates higher than 100 μm/h, as compared to 5 μm/h for the standard case. The chlorinated precursor used is methyltrichlorosilane (MTS), CH 3SiCl 3, but since MTS contains both silicon and carbon, with the C/Si ratio 1, we have also added silane or ethylene to optimise the C/Si ratio in order to improve the morphology of the epitaxial layers. We present studies on how the growth rate depends on both the flow of MTS and C/Si ratio. The morphology of the grown epitaxial layer has been investigated using Nomarski microscope and atomic force microscope showing extremely smooth surface and low epi-defect density. The net doping has been determined using capacitance-voltage measurements. Low temperature photoluminescence and high-resolution X-ray diffraction confirm the high quality of the grown epilayers.