Scanning tunnelling microscopic images of the As-rich 2 x 3 reconstruction of the (001) surface were analyzed. It was shown that this surface did not have 2 x 3 symmetry, but was instead composed of domains of 4 x 3 and c(4 x 6) unit cells. Study of the scanning tunnelling microscopic images indicated that occupied and unoccupied surface electronic states were localized at different sites within the 4 x 3 unit cell. A new structural model was proposed for the 2 x 3 reconstruction.

I.Chizhov, G.Lee, R.F.Willis, D.Lubyshev, D.L.Miller: Physical Review B, 1997, 56[3], 1013-6