The growth of low resistivity, heavily Al-doped 4H–SiC thick epilayers by hot-wall chemical vapor deposition

Abstract

Heavily Al-doped 4H–SiC thick epilayers (∼90μm) were grown on 3-in n+ 4H–SiC wafers by using the hot-wall CVD method. On the purpose of enhancing incorporated Al-dopant concentration, the growth condition dependence of the Al incorporation behavior in the heavy doping range near Al solubility limit in 4H–SiC was investigated by varying the growth parameters, i.e., growth rate, pressure, temperature and Al-dopant source flow rate. A series of thick epilayers possessing Al-dopant concentration from 9.6×1019 to 4.7×1020cm−3 were obtained. Among them, the epilayer with Al-dopant concentration of 3.5×1020cm−3 demonstrates a comparably low resistivity of 16.5mΩcm as that of commercial n+ 4H–SiC wafer. The incorporated Al-dopant concentration dependences on surface morphology, crystalline quality and crystal structures of the heavily Al-doped thick epilayers on n+ 4H–SiC substrates were characterized and discussed.