An analysis was made of the energetics of possible candidates for a structural model of the α-SiC(00•1)-(√3 x √3) surface reconstruction. The analysis was based upon quantum chemical calculations of MNDO type (AM1 parameterization). The results indicated that, among the models tested, the energetically most stable structure was made of C6 rings bonded to the stoichiometric substrate via a 2/3 monolayer of silicon. The structure had one Si dangling bond per (√3 x √3) surface unit cell and as such should normally represent a conducting surface. However, instead of being exposed, the dangling bonds here were localized on the Si substrate atoms below the centers of the C6 rings. The photoemission signal from the dangling bond states was then likely to be suppressed, thus making the surface appear semiconducting in photo-emission experiments. Moreover, the pattern of the core level shifts of the SiC(00•1)-(√3 x √3) surface agreed with the number of charge inequivalent Si and C atoms around the surface in the proposed model.

A New Carbon-Rich Model of the α-SiC(0001)-(√3 x √3) Surface Reconstruction. P.Badziag: Surface Science, 1998, 412-413, 502-8