A new phase with spontaneous atomic ordering on the sub-lattice was found in Al0.48In0.52As grown on exact (001)InP substrate by molecular-beam epitaxy. The atomic arrangement was 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 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 unequivocally demonstrated that surface reconstruction plays a central role in ordered structure formation. Band-gap reductions of ∼80 and ∼30meV were observed for the new ordered phase and the CuPt-type phase, respectively.

Observation of a New Ordered Phase in AlxIn1-xAs Alloy and Relation between Ordering Structure and Surface Reconstruction during Molecular-Beam-Epitaxial Growth. A.Gomyo, K.Makita, I.Hino, T.Suzuki: Physical Review Letters, 1994, 72, 673-6