Molecular beam epitaxial growth and characterization of zinc telluride, aluminum antimonide, and gallium antimonide for the development of optoelectronic devices
Abstract
A wide band-gap light emitter has many potential optoelectronic device applications. The wide-gap ZnTe has difficulties associated with amphoteric doping. Therefore, a ZnTe/AlSb heterojunction has been studied. Computer simulations indicate that the p-ZnTe/n-AlSb heterojunction is expected to have a favorable conduction band line-up for fabricating wide-gap pn-junction light emitting devices. Two isolated II-VI and III-V molecular beam epitaxial growth chambers that were connected by an ultra high vacuum transfer tube were used to avoid unintentional doping. ZnTe epilayers were nucleated on GaSb substrates, homoepitaxial GaSb epilayers, and pseudomorphic AlSb epilayers. To the best of the authors knowledge, the latter constitutes the first ZnTe/AlSb heterojunction. Reflection high energy diffraction (RHEED) study of the nucleation of ZnTe indicates a three dimensional nucleation on a GaSb substrate. In contrast, a two dimensional nucleation was indicated for ZnTe nucleation on epilayers of AlSb and GaSb. The optical properties of both thick and pseudomorphic epilayers of ZnTe were studied. Free exciton spectral components have been observed in the photoluminescence of both thick (strain relaxed) and pseudomorphic ZnTe epilayers. The microstructural quality of the ZnTe was studied by TEM and X-ray rocking curves. The study of Sb incorporation into ZnTe epilayers grown on semi-insulating GaAs substrates was studied with Hall, XPS, and SIMS data. The microstructural and properties of AlSb and GaSb epilayers were studied by TEM and X-ray rocking curves. The GaSb growth conditions were optimized to produce X-ray rocking curves from homoepitaxial GaSb with full width half maximums (FWHM) from the (004) diffraction pattern of less than 12 arc seconds. Doping and transport experiments of AlSb and GaSb involving PbSe and PbTe were also studied for a variety of epilayer growth conditions.
Degree
Ph.D.
Advisors
Gunshor, Purdue University.
Subject Area
Electrical engineering
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