Hydrogenation of 6H-SiC as a surface passivation stable in air

We have terminated the hexagonal (0001) and (000 (1) over bar) surfaces of 6H-SiC with a monolayer of hydrogen by exposing the SiC crystal to pure hyd rogen at elevated temperatures. The surfaces exhibit sharp, background-free , and unreconstructed LEED patterns and the photoemission spectra show only bulk-related Si and C components and give no indication of additional unwa nted adsorbates. On the Si-terminated (0001) surface, a sharp doublet at 21 30 cm(-1) with a splitting of 6 cm(-1) is observed in surface-sensitive inf rared spectroscopy, which is due to monohydride Si-H stretching modes. The origin of the splitting is discussed. The hydrogenated surfaces are passiva ted chemically and electronically. The oxygen uptake is less than 2 at.% af ter 2 h air exposure without any sign of Si-O or C-O bond formation. The su rface Fermi level is unpinned and exhibits its bulk position on n- and p-ty pe samples. (C) 2001 Elsevier Science B.V. All rights reserved.