Oxidation studies of 4H-SiC(0001) and (0001)

The results of a photoemission study of Si- and C-terminated 4H SiC surfaces after different oxygen exposures are presented and discussed. The surfaces were oxidized gradually from 1 to 1.2 x 10(6) L at both room temperature and at 800 degreesC. Recorded Si 2p and C 1s spectra show at both temperatures only two oxidations states, Si1- and Si4- for the Si-terminated surface and Si2+ and Si4+ for the C-terminated surface, For the Si-terminated surface, no carbon containing by-product can be detected at the interface or at the surface after the largest exposure investigated. For the C-terminated surface, oxygen exposures are shown to affect the surface related carbon components quite strongly and the Si2+ oxidation state is interpreted to originate from a mixture of Si-O-C bonding, The surface/interface related carbon decreases dramatically after the largest exposure investigated but is not eliminated as on the Si-terminated surface. For the latter, a clean and well ordered root3 surface is shown to be possible to re-create by in situ heating even after the largest oxygen exposures made. (C) 2002 Elsevier Science B.V. All rights reserved.