Potentialities of AlGaN/GaN Heterostructures Grown on 2°-Off 4H-SiC Substrates

Abstract

So far, most of the SiC homoepitaxy has been realized on 8-deg-off and 4-deg-off substrates, whereas GaN heteroepitaxy is done on SiC on-axis (up to 0.3 deg off). As 6-inch SiC wafers are being introduced into the market, a decrease of the substrate off-cut to 2 deg for SiC homoepitaxy is desirable to reduce the manufacturing costs. If both, GaN heteroepitaxy and SiC homoepitaxy are successful on 2-deg-off SiC substrates, this would pave the way to monolithic integration of both kinds of devices, as well as to obtain cheap insulating SiC substrates for AlGaN/GaN microwave and THz devices. In this work, we present our present status of AlGaN/GaN growth on SiC 2-deg off. Comparing to the on-axis situation, we obtained similar structural (XRD and TEM data) and electrical characteristics, but not morphological ones. Therefore, we propose two ways of a decrease of AlGaN surface roughness when grown on SiC 2 deg-off: i) by planarization, ii) by lateral patterning.