First-principles study of InP and GaP(001) surfaces

The dependence of the GaP and InP(0 0 1) surface reconstructions on the chemical potentials of their constituents is explored. Based on first-principles pseudopotential plane-wave calculations the surface phase diagram is obtained. For both GaP(0 0 1) and Inp(0 0 1) surfaces, P-top dimer reconstructions are predicted for P-rich conditions, while for group III-element rich preparations a mixed dimer (III-P) on a complete III-layer is favoured. For GaP, in addition, a Ga-top dimer reconstruction seems to be a possibility for very Gallium rich growth conditions. STM images are calculated in order to contribute to a solution of the structural puzzle. (C) 2001 Published by Elsevier Science B.V.