Scanning tunnelling microscopy was used to investigate the microscopic structure of the P-rich (2 x 1) reconstruction of (001). Low-energy electron diffraction patterns revealed a (2 x 1)/(2 x 2) periodicity, with streaks in the [¯110] direction. The images revealed rows, in the [110] direction, which were formed from randomly distributed (2 x 2)/c(2 x 2)/c(4 x 2)-like local structures; plus many defects. This disorder explained the (2 x 1)-like low-energy electron diffraction pattern. The structure of the rows was explained in terms of P dimers which were directed along the [110] direction and adsorbed on a complete P layer beneath. Prolonged annealing at 350C caused the successive desorption of single P dimers. The low-energy electron diffraction pattern remained essentially unaffected, and atomic-resolution scanning tunnelling microscopic images revealed zig-zag chains in the [110] direction which were separated by twice the lattice constant. Two adjacent rows could be in, or out of, phase; thus resulting in either a p(2 x 2) or c(4 x 2) reconstruction.

Atomic Surface Structure of Phosphorous-Terminated InP(001) Grown by MOVPE P.Vogt, T.Hannappel, S.Visbeck, K.Knorr, N.Esser, W.Richter: Physical Review B, 1999, 60[8], R5117-20