Computer calculations of semiconductor surface structures

Abstract

Surface energies have been computed for Ge and Si using the H model for the surface structure. The energy is found to be less than for the “ideal” structure. The interatom potential function used was of Morse form with the two adjustable parameters, D the bond energy, and a the potential shape factor, being specified by comparing computed surface energies, elastic constants c 11, and sublimation energies with experiment. By using the principle of minimum surface free energy, numerical values for the surface atom positions are then derived. These agree closely with previous predicted values for Ge based on LEED analysis. For III–v compounds the ratios of surface stress related energies for the A and B faces, are computed in terms of different Morse functions for the A and B faces, and incorporated with available experimental data. These provide limits on the differences in surface potentials between the A and B faces.