OBSERVATION OF TRIPLE-PERIOD-A TYPE ATOMIC ORDERING IN Sb-DOPED Ga0.5In0.5P ALLOYS

Triple-period-A (TP-A) type ordering of atoms has been observed in Sb-doped Ga0.5In0.5P grown by metal-organic VPE on (001)GaAs at approx 650 C. The appearance of TP-A type ordering at such a high temperature with a very low flow-rate for Sb is believed to result from the formation of (2 x 3) surface reconstruction with double Sb-rich-group-V-surface-layers during growth, due to the antimony's low vapor pressure. Sb constituted as little as 1.6% of the atoms in the group-V sublattice. A peculiar characteristic in the pattern of the diffuse scattering from Sb-doped Ga0.5In0.5P was interpreted to result from the novel orientation of the shallow disk-shaped domains of TP-A type ordering. 15 refs.