Growth and Characterization of Molecular Beam Epitaxial Gallium-Arsenide Antimonide and Gallium-Arsenide Antimonide/gallium-Arsenide Superlattices

Abstract

135 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1987.Described in this thesis are the molecular beam epitaxial growth and characterization of GaAs\sb{\rm 1-x}Sb\sb{\rm x} films and GaAs\sb{\rm 1-x}Sb\sb{\rm x}/GaAs strained layer superlattices. The methods used to reproducibly grow GaAs\sb{\rm 1-x}Sb\sb{\rm x} across its entire composition range are detailed. The resulting film surface morphologies and microstructures are investigated by optical and electron microscopy. Significant atomic clustering and ordering effects are observed in alloys of metastable composition. Optical characterization of these alloys shows that good quality material can be obtained, but that the major limitation to the quality of these materials is related to the film microstructure. Electrical measurements on unintentionally-doped layers reveal p-type conductivity due to two distinct acceptor levels. Hole mobilities are qualitatively explained in a model that assumes a dominant alloy scattering mechanism.Strained layer GaAs\sb{\rm 1-x}Sb\sb{\rm x}/GaAs superlattices are characterized by x-ray diffraction, photoluminescence, photoreflectance, and optical absorption. Structural parameters derived from a kinematical x-ray diffraction model are used in conjunction with the results of optical characterization and an envelope function approximation bandstructure model to estimate the GaAs/GaSb band alignment. These results indicate that the superlattices are Type II.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD