Direct Atomic Site Determination of Foreign Atoms in a Crystal Surface Layer by X-Ray Photoelectron Diffraction

X-ray photoelectron diffraction (XPED) patterns for A12p, Ga3d and As3d from Ga1-x Al x As (110) are measured. XPED patterns for Ga3d and As3d show characteristic differences due to the difference in atomic sites of Ga and As atoms in Ga1-x Al x As crystal. On the other hand, the XPED pattern for A12p is almost identical to that for Ga3d. The results show a clear corresondence between XPED patterns and sites of photoelectron emitter atoms in the crystal. Based on the results, applicability of XPED measurements to direct atomic site determination of foreign atoms in a crystal surface layer is discussed.