SURFACE ENERGIES FOR MOLECULAR-BEAM EPITAXY GROWTH OF HGTE AND CDTE

We present results for the surface binding energies for HgTe and CdTe that will serve as input for molecular beam epitaxy growth models. We have found that the surface binding energies are surface orientation dependent and are not simply proportional to the number of first-neighbor bonds being made to the underlying layer. Moreover, because of the possibility of charge transfer between cation and anion surface states, one may have large differences between the binding energy for the first and the last atom in a given layer, and these differences will be different for the narrow-gap, less ionic materials than for the wide-gap, ionic materials. We also find that the surface states associated with an isolated surface atom or vacancy are extended in materials with small gaps and small effective masses, and thus call into question the modeling of surface binding by simple pair interactions.