Chemical vapor cleaning of 6H-SiC surfaces

The techniques (temperature range of study) of in situ thermal desorption ( 500-1100 degrees C) and chemical vapor cleaning (CVC) via exposure to SiH4 and/or C2H4 (750-1100 degrees C) have been investigated for preparing 6H Si C [(0001)(Si), (000 (1) over bar)(C), (11 (2) over bar 0), and (10 (1) over bar 0)] surfaces suitable for epitaxial growth of SiC and III-nitride film s, and are compared with regard to surface purity, stoichiometry, and struc tural order. Oxide removal below the detection limits of Auger electron spe ctroscopy was achieved for all orientations via annealing in 200 L SiH4 at 850-900 degrees C or approximate to 200 degrees lower than necessary by the rmal desorption. No non-SiC carbon was detected on the surface by X-ray pho toelectron spectroscopy. An approximately one-tenth of a monolayer of oxyge n coverage and significant quantities of non-SiC carbon were detected for a ll 6H SiC surfaces prepared by thermal desorption. In contrast to the predo minantly non-SiC carbon-rich surfaces prepared by thermal desorption, the s toichiometry of the SiC surfaces prepared by CVC could be manipulated from Si-rich to C-rich without non-SiC carbon formation by either extending the SiH4 exposures or by following with C2H4 exposure. The latter surfaces also had lower concentrations of both oxygen and non-SiC carbon and increased s urface order. (C) 1999 The Electrochemical Society. S0013-4651(98)11-055-8. All rights reserved.