Investigations of the Sb/CdTe(100)-(2×1) interfacial structure with photoemission

Abstract

Clean CdTe(100) surfaces were generated by molecular beam epitaxy (MBE). High energy electron diffraction (HEED) and photoemission were used to determine surface quality and to make comparisons with surfaces generated via cycles of ion sputtering and annealing. Photoemission, HEED, and Auger electron spectroscopy were used to study the properties of the Sb/CdTe(100)-(2×1) interface. Photoemission spectra of the Cd 4d and Te 4d core levels showed no changes when Sb was deposited on the clean surface at room temperature. HEED showed that the Sb films where polycrystalline. Annealing caused the polycrystalline films to convert to a sharp (2×2) reconstructed surface. Auger spectra indicated that annealing causes desorption of all but 1 2 monolayer of Sb from the surface. Photoemission spectra of the Cd 4d core level showed a significant depletion in intensity of the surface shifted component. The Sb 4d core level spectrum showed a large shift (0.72 eV) in binding energy in converting from polycrystalline to the (2×2) surface. A model is proposed for the (2×2) surface structure in which Sb atoms are bonded to two Cd atoms,and Cd atoms are bonded to only one Sb atom. In order to satisfy dangling bonds, the Sb atoms also form dimer bonds with each other.