Sublimation growth of an in-situ-deposited layer in SiC chemical vapor deposition on 4H-SiC(1 1 (2)over-bar 0)

Homoepitaxial growths of 4H-SiC(1 1 (2) over bar 0) epitaxial layers have been achieved using chemical vapor deposition from 1250 to 1600 degrees C and two process routes: (1) with and (2) without the addition of SiH4 and C2H4 to the growth ambient. An activation energy of 3.72 eV/atom (359 kJ/mol) was determined for the former route and associated with either reactions in the gas phase or the potential barrier associated with the temperature-dependent sticking coefficient. The activation energy for the latter route was 5.64 eV/atom (544 kJ/cool), which is consistent with published values for SiC sublimation epitaxy. Sublimation dominated the growth process at temperature >= 1600 degrees C. The same effect resulted in the in-situ deposition of a thin film during the heating stage of route (1). At 1450 degrees C this layer was similar to 100 nm thick and exhibited a specular surface microstructure with a roughness of 0.31 nm RMS. The in-situ-deposited layer was thus employed as an intermediate layer prior to epitaxial layer growth using route (1) at similar to 1450 C. Regions free of one- and two-dimensional defects were observed using cross-sectional transmission electron microscopy. Distinct interfaces were not observed between the substrate and the epitaxial layers. (C) 2008 Elsevier B.V. All rights reserved.