A new phase with spontaneous atomic ordering on the sub-lattice was found in In0.52Al0.48As which had been grown onto exactly (001)InP substrates by means of molecular-beam epitaxy. The atomic arrangement consisted of a periodic sequence of {111}A planes in a unit of AlxIn1-x/AlyIn1-y/AlzIn1-z on the group-III sub-lattice. The surface reconstruction during growth was 2 x 3. A CuPt-type ordered phase was observed in crystals which were grown at higher temperatures, where the reconstruction was 2 x 1. This correlation, with respect to periodicity and direction between the reconstructions and the types of ordered phase, demonstrated that surface reconstruction played a central role in ordered structure formation. Band-gap reductions of about 0.080 and 0.830eV were observed for the new ordered phase and for the CuPt-type phase, respectively.

A.Gomyo, K.Makita, I.Hino, T.Suzuki: Physical Review Letters, 1994, 72[5], 673-6