DPBs-free and polytype controlled growth of SiC via surface etching on on-axis 6H-SiC(0 0 0 1)

Abstract

The effects of etching on-axis 6H-SiC(0 0 0 1) substrates in H 2 and HCl/H 2 on the surface defects and the polytype of subsequently deposited SiC films are reported. The surface step periodicity and height varied with etching conditions and whether a SiC coating was present or absent on the susceptor. The 3C-SiC films grown on etched substrates had higher crystal quality and lower double positioning boundary (DPB) densities compared to the 3C-SiC films grown on the as-received substrates. DPB-free growth of 3C-SiC was achieved via step flow growth on etched substrates with well-defined three-bilayer step heights at high temperatures (1475°C) and low silane concentrations (<50 ppm SiH 4/H 2). A mechanism is proposed to explain the DPBs-free growth of the 3C-SiC films based on the metastable step flow growth and the control of the number and the sites where 3C-SiC nucleates.