First-principles study of GaP(001) surfaces

First-principles total energy calculations have been performed on GaP(001) surfaces to determine the disordered structure during phase transitions. The Ga-rich and P-rich (2 x 1), (2 x 2) and (2 x 4) structures were discussed. The surface phase diagram showed that a disordered phase exist during phase transition between (2 x 1) and (2 x 4) structures, which was assigned to be the coexistence of three ordered structures: 02(2 x 4), 8(2 x 4) and Ga(2 x 1)md. This result does not support the observations that the disordered structure is a mixture of alpha.(2 x 4) and beta(2 x 4) [D.C. Law, Y. Sun, R.F. Hicks, J. Appl. Phys. 94 (2003) 6175]. Generally, good agreement in structural parameters was obtained with previous results. Total and partial density of states analysis for three stable phases was presented. (c) 2006 Published by Elsevier B.V.