Core-level photoemission study of the Bi-GaAs(111) A interface

Core-level photoemission spectra of the As 3d, Ga 3d and Bi 5d core levels were recorded for the Bi-GaAs (111)A-(2 X 2) surface. From the early stages of Bi growth, there are two distinct chemical environments for Bi. Surface Bi is bonded to both As and Ga atoms. The deposition of approximately 1 ML of Bi removes the dangling bonds from the surface As and Ga atoms, which a re associated with the (2 X 2) vacancy-buckling structure. Annealing to 350 degrees C reverses this process and surface dangling bonds for Ga reappear . When the Bi had fully desorbed at 425 degrees C, photoemission and LEED r esults showed that the surface recovers the (2 X 2) vacancy structure but w ith a larger degree of surface disorder than that found before the depositi on of Bi. (C) 2000 Elsevier Science B.V. All rights reserved.