DPBs-free and polytype controlled growth of SiC via surface etching on on-axis 6H-SiC(0001)

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 fil ms are reported. The surface step periodicity and height varied with etchin g conditions and whether a SiC coating was present or absent on the suscept or. The SC-SIG films grown on etched substrates had higher crystal quality and lower double positioning boundary (DPB) densities compared to the 3C-Si C 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 degreesC) and low silane co ncentrations (< 50ppm SiH4/H-2) A mechanism is proposed to explain the DPBs -free growth of the 3C-SiC films based on the metastable step flow growth a nd the control of the number and the sites where 3C-SiC nucleates. (C) 2001 Elsevier Science B,V. All rights reserved.