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

Abstract

We have terminated the hexagonal (0001) and ( 000 1 ̄ ) surfaces of 6H-SiC with a monolayer of hydrogen by exposing the SiC crystal to pure hydrogen 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 unwanted adsorbates. On the Si-terminated (0001) surface, a sharp doublet at 2130 cm −1 with a splitting of 6 cm −1 is observed in surface-sensitive infrared spectroscopy, which is due to monohydride SiH stretching modes. The origin of the splitting is discussed. The hydrogenated surfaces are passivated chemically and electronically. The oxygen uptake is less than 2 at.% after 2-h air exposure without any sign of SiO or CO bond formation. The surface Fermi level is unpinned and exhibits its bulk position on n- and p-type samples.