The structures of clean or (NH4)2Sx-treated (111)A and (111)B surfaces were studied by using low-energy electron diffraction, inverse photo-emission spectroscopy, and X-ray or ultra-violet photo-emission spectroscopy. The thermal stability of the treated surfaces upon annealing in an ultra-high vacuum was also investigated. A diffuse (1 x 1) low-energy electron diffraction pattern appeared in the case of treated (111)A and (111)B surfaces which were annealed at 230 and 330C, respectively. Upon annealing the (111)B sample at 380C, the (1 x 1) structure remained and the low-energy electron diffraction spots became clearer. In the case of (111)A samples which were annealed at 380C, the pattern changed to a clear (2 x 2) structure which was observed for the first time on sulfurized (111) surfaces of III-V compounds. The S was completely desorbed from both the (111)A and (111)B surfaces at 440C, which exhibited the (2 x 2) and (1 x 1) structures, respectively. Inverse photo-emission spectroscopic and photo-emission spectroscopic data indicated that unoccupied and occupied dangling bonds disappeared from S-adsorbed (111)A-(2 x 2) and (111)B-(1 x 1) surfaces, respectively. The 2p spectra of S showed that it was bonded to both In and As on (111)B surfaces which were annealed below 340C, and was bonded only to In at 420C. On the other hand, it was bonded only to In on the (111)A surface; with or without annealing.

Surface structures and electronic states of clean and (NH4)2Sx-treated InAs(111)A and (111)B S.Ichikawa, N.Sanada, N.Utsumi, Y.Fukuda: Journal of Applied Physics, 1998, 84[7], 3658-63