Growth, optical properties, and optimization of infrared optoelectronic materials
Another important infrared material system is InAsSb and the strain-balanced InAs/InAsSb superlattice on GaSb. Detailed examination of X-ray diffraction, photoluminescence, and spectroscopic ellipsometry data provides the temperature and composition dependent bandgap of bulk InAsSb. The unintentional incorporation of approximately 1% Sb into the InAs layers of the superlattice is measured and found to significantly impact the analysis of the InAs/InAsSb band alignment. In the analysis of the absorption spectra, the ground state absorption coefficient and transition strength of the superlattice are proportional to the square of the electron-hole wavefunction overlap; wavefunction overlap is therefore a major design parameter in terms of optimizing absorption in these materials. Furthermore in addition to improvements through design optimization, the optical quality of the materials studied is found to be positively enhanced with the use of Bi as a surfactant during molecular beam epitaxy growth.
A software tool is developed that calculates and optimizes the miniband structure of semiconductor superlattices, including bismide-based designs. The software has the capability to limit results to designs that can be produced with high structural and optical quality, and optimized designs in terms of maximizing absorption are identified for several infrared superlattice systems at the GaSb lattice constant. The accuracy of the software predictions are tested with the design and growth of an optimized mid-wave infrared InAs/InAsSb superlattice which exhibits superior optical and absorption properties.]]>autWebster, Preston ThomasthsJohnson, Shane RdgcZhang, Yong-HangdgcMenéndez, JosedgcVasileska, DragicapblArizona State UniversityengPartial requirement for: Ph.D., Arizona State University, 2016Includes bibliographical references (pages 153-157)Field of study: Electrical engineeringby Preston Thomas Websterhttps://hdl.handle.net/2286/R.I.3940000Doctoral DissertationAcademic thesesxi, 167 pages : illustrations (some color)114700564151630347740154755adminIn CopyrightAll Rights Reserved2016TextElectrical EngineeringMaterials Sciencequantum physicsAbsorptionBismuthInAsBiInAs/InAsSbsuperlatticesurfactantBismuth alloysTernary alloysSuperlattices as materialsOptoelectronic devices