Bismuth incorporation and lattice contraction in GaSbBi and InSbBi
III–V-Bi compounds have received considerable attention recently due to a number of interesting material properties. For example, adding a small amount of Bi atoms in conventional III–Vs leads to a large bandgap reduction that occurs predominately in the valence band, about 88 meV/%Bi in GaAsBi. The Bi incorporation affects only the valence band structures and has little influence on electrons. Compared with dilute nitrides, the electron mobility of dilute GaAsBi is much less affected and photoluminescence intensity increases with the Bi incorporation. Dilute GaAsBi also introduces a large spin-orbit split and it has been suggested to use this property to suppress Auger recombination for 1.55 µm lasers on GaAs [1]. So far most experimental studies have been focused on growth of GaAsBi [2], but very little on GaSbBi and InSbBi. Here we report growth of dilute GaSbBi and InSbBi using molecular beam epitaxy (MBE). We have optimized growth conditions aiming at achieving maximum Bi incorporation. Surprisingly X-ray diffraction (XRD) revealed lattice contraction in GaSbBi and InSbBi although Bi atoms have a large atomic radius.
Group III-V Bismide Materials Grown by Liquid Phase Epitaxy
Bi containing III–V compound semiconductors have become important in the last few years for many potential device applications. Molecular beam epitaxy and metalorganic vapor phase epitaxy techniques have mostly been used for the growth of these compounds. We review here the application of the simple liquid phase epitaxy (LPE) technique for the growth of some members of the III–V-Bi series. Due to the restrictions of limited solubility of Bi in III–V solids, use of LPE has so far been limited to the growth of InSbBi and GaSbBi. We describe here details of the growth procedure and the characterization of these two ternaries by different groups with special emphasis on the structural, luminescence, and band gap reduction properties. Theoretical model based on diffusion of Bi across an LPE growth model is described with a view to optimize the growth parameters. Reference is also made to the melt growth of bulk crystals of these compounds and to the LPE growth of InPBi and InAsSbBi epitaxial layers.
Composite monolayer fabrication by an arc-spray process
A single layer (monotape) technique for fabricating complex high-temperature tungsten-fiber-reinforced superalloy composites is proposed. The fabrication of sheets of arc-sprayed monotape 38 cm wide and 122 cm long has been demonstrated. Composites fabricated using the method are shown to have equal tensile strength and a cleaner matrix than composites fabricated from powder metal cloth monotapes, and the present technique is less expensive than the powder metal fabrication techniques.