X-RAY PHOTOELECTRON DIFFRACTION FROM THE CDTE(111)A POLAR SURFACE

Polar and azimuthal X-ray photoelectron diffraction (XPD) data on a CdTe(111)A (Cd terminated) surface are reported and discussed on the basis of a single scattering cluster (SSC) theory. Significantly distinct patterns are predicted for the two different (111)A and (111)B polar surfaces, suggesting that the XPD technique is a valid tool for the absolute determination of the surface polarity. Moreover, the azimuthal diffraction patterns obtained at grazing polar angles (so that the probed surface region is very shallow) revealed details which can be elucidated assuming either a surface relaxation, where Cd and Te atoms of the outermost double layer are almost coplanar, or a (2 square-root 3 x 2 square-root 3) R30-degrees- surface reconstruction.