ATOMIC ORDERING IN INGAASP AND INGAAS GROWN BY ATMOSPHERIC-PRESSURE METALORGANIC CHEMICAL VAPOR-DEPOSITION

We report on a systematic study of atomic ordering in InGaAsP and InGaAs grown by atmospheric pressure metalorganic chemical vapor deposition. InGaAsP lattice matched to InP, grown in a temperature range of 625-650-degrees-C, reveals atomic ordering on the (111) plane (variant I) and the (111BAR) plane (variant II) of the group III sublattice. The extent of atomic ordering increases with decreasing growth temperature and increasing In to Ga ratio. No orderings are observed in InGaAsP grown at 700-degrees-C or in In0.53Ga0.47As lattice matched to InP at all our growth temperatures, in contrast to the commonly believed occurrence of maximum ordering at 1/1 In to Ga ratio. The facts that these conditions differ significantly from the reported conditions for InGaAsP grown by other techniques strongly suggests that the atomic ordering formation is controlled by the surface kinetics and growth environment, i.e., chemistry at the reactive gas-solid surface, fluid dynamics of the reactive gases, and growth temperature, rather than the composition and growth temperature. A fine structure observed in the superspots associated with the atomic ordering in the electron diffraction pattern indicates a possible superlattice structure formed by alternating variant I and variant II ordered layers. Misfit strain as well as sulfur dopant are shown to have no effect on the atomic ordering. Zinc dopant, however, totally eliminates the atomic ordering and shifts the energy band gap to a larger band gap.