High growth rate 4H-SiC epitaxial growth using dichlorosilane in a hot-wall CVD reactor

摘要

Thick, high quality 4H-SiC epilayers have been grown in a vertical hot-wall chemical vapor deposition system at a high growth rate on (0001) 8° off-axis substrates. We discuss the use of dichlorosilane as the Si-precursor for 4H-SiC epitaxial growth as it provides the most direct decomposition route into SiCl_2, which is the predominant growth species in chlorinated chemistries. A specular surface morphology was attained by limiting the hydrogen etch rate until the system was equilibrated at the desired growth temperature. The RMS roughness of the grown films ranged from 0.5-2.0 nm with very few morphological defects (carrots, triangular defects, etc.) being introduced, while enabling growth rates of 30-100 um/h, 5-15 times higher than most conventional growths. Site-competition epitaxy was observed over a wide range of C/Si ratios, with doping concentrations < 1 x 10~(14)cm~(-3) being recorded. X-ray rocking curves indicated that the epilayers were of high crystallinity, with linewidths as narrow as 7.8 arcsec being observed, while microwave photoconductive decay (uPCD) measurements indicated that these films had high injection (ambipolar) carrier lifetimes in the range of 2 us.