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Title: Electronic and optical properties of semiconductors: A study based on the empirical tight binding model

Abstract

This study is a theoretical investigation of the electronic and optical properties of intrinsic semiconductors using the orthogonal empirical tight binding model. An analysis of the bulk properties of semiconductors with the zincblende, diamond and rocksalt structures has been carried out. The author has extended the work of others to higher order in the interaction integrals and derived new parameter sets for certain semiconductors which better fit the experimental data over the Brillouin zone. The Hamiltonian of the heterostructures is built up layer by layer from the parameters of the bulk constituents. The second part of this work examines a number of applications of the theory. A new microscopic derivation of the intervalley deformation potentials is presented within the tight binding representation and computes a number of conduction-band deformation potentials of bulk semiconductors. The author has also studied the electronic states in heterostructures and have shown theoretically the possibility of having barrier localization of above-barrier states in a multivalley heterostructure using a multiband calculation. Another result is the proposal for a new [open quotes]type-II[close quotes] lasing mechanism in short-period GaAs/AlAs super-lattices. As for the author's work on the optical properties, a new formalism, based on the generalized Feynman-Hellmann theorem, formore » computing interband optical matrix elements has been obtained and has been used to compute the linear and second-order nonlinear optical properties of a number of bulk semiconductors and semiconductor heterostructures. In agreement with the one-band effective-mass calculations of other groups, the more elaborate calculations show that the intersubband oscillator strengths of quantum wells can be greatly enhanced over the bulk interband values.« less

Authors:
Publication Date:
Research Org.:
Worcester Polytechnic Inst., MA (United States)
OSTI Identifier:
7102735
Resource Type:
Miscellaneous
Resource Relation:
Other Information: Thesis (Ph.D.)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; SEMICONDUCTOR MATERIALS; BAND THEORY; ELECTRICAL PROPERTIES; OPTICAL PROPERTIES; HETEROJUNCTIONS; THEORETICAL DATA; DATA; INFORMATION; JUNCTIONS; MATERIALS; NUMERICAL DATA; PHYSICAL PROPERTIES; SEMICONDUCTOR JUNCTIONS 360606* -- Other Materials-- Physical Properties-- (1992-); 665400 -- Quantum Physics Aspects of Condensed Matter-- (1992-)

Citation Formats

Lew, Yan Voon, L.C. Electronic and optical properties of semiconductors: A study based on the empirical tight binding model. United States: N. p., 1993. Web.
Lew, Yan Voon, L.C. Electronic and optical properties of semiconductors: A study based on the empirical tight binding model. United States.
Lew, Yan Voon, L.C. 1993. "Electronic and optical properties of semiconductors: A study based on the empirical tight binding model". United States. doi:.
@article{osti_7102735,
title = {Electronic and optical properties of semiconductors: A study based on the empirical tight binding model},
author = {Lew, Yan Voon, L.C.},
abstractNote = {This study is a theoretical investigation of the electronic and optical properties of intrinsic semiconductors using the orthogonal empirical tight binding model. An analysis of the bulk properties of semiconductors with the zincblende, diamond and rocksalt structures has been carried out. The author has extended the work of others to higher order in the interaction integrals and derived new parameter sets for certain semiconductors which better fit the experimental data over the Brillouin zone. The Hamiltonian of the heterostructures is built up layer by layer from the parameters of the bulk constituents. The second part of this work examines a number of applications of the theory. A new microscopic derivation of the intervalley deformation potentials is presented within the tight binding representation and computes a number of conduction-band deformation potentials of bulk semiconductors. The author has also studied the electronic states in heterostructures and have shown theoretically the possibility of having barrier localization of above-barrier states in a multivalley heterostructure using a multiband calculation. Another result is the proposal for a new [open quotes]type-II[close quotes] lasing mechanism in short-period GaAs/AlAs super-lattices. As for the author's work on the optical properties, a new formalism, based on the generalized Feynman-Hellmann theorem, for computing interband optical matrix elements has been obtained and has been used to compute the linear and second-order nonlinear optical properties of a number of bulk semiconductors and semiconductor heterostructures. In agreement with the one-band effective-mass calculations of other groups, the more elaborate calculations show that the intersubband oscillator strengths of quantum wells can be greatly enhanced over the bulk interband values.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1993,
month = 1
}

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  • Described in this thesis is an investigation of some fundamental physical properties of both zincblende and wurtzite Group III - Nitride wide bandgap semiconductor materials. All of the thin films studied were grown by plasma-enhanced molecular beam epitaxy on either GaAs and SiC substrates. This growth method proved to be suitable for nitride epitaxial growth although compromises between the plasma power and the crystal growth rate had to be sought. The zincblende polytypes of GaN and InN were studied with the intent of evaluating their potential as a wide bandgap semiconductor system for short wavelength optical devices. The metastability ofmore » these crystals has led us to the conclusion that the zincblende nitrides are not a promising candidate for these applications due to their tendency to nucleate wurtzite domains. Bulk samples of zincblende GaN and InN and wurtzite GaN, AlN and InN were studied by x-ray photoemission spectroscopy (XPS) in an effort to determine their valence band structure. The authors report the various energies of the valence band density of states maxima as well as the ionicity gaps of each material. Wurtzite GaN/AlN and InN/AlN heterostructures were also investigated by XPS in order to estimate the valence band discontinuities of these heterojunctions. The authors measured valence band discontinuities of [Delta]E[sub v][sup GaN/AlN] = 0.4 [+-] 0.4 eV and [Delta]E[sub v][sup InN/AlN] = 1.1 [+-] 0.4 eV. The results indicate that both systems have heterojunction band lineups fundamentally suitable for common optical device applications.« less
  • The first principles Unrestricted Hartree-Fock Cluster procedure has been applied to investigate the electronic structures and associated hyperfine properties of several categories for solid systems. The first category is concerned with the location and nuclear quadrupole interactions (NQI) of fluorine impurity centers in crystalline silicon (c-Si). The Time Differential Perturbed Angular Distribution experiments show that when excited nuclear static fluorine ([sup 19]F*) is implanted into c-Si, two [sup 19]F* centers are formed characterized by two unique axially symmetric electric field gradients (efg). Models have been examined to determine the stable [sup 19]F* sites in the bulk c-Si. The two models,more » IB and AB, are also able to explain the experimental [sup 19]F* NQI data in crystalline germanium where two centers with axially symmetric efg are observed. The experimental trends of [sup 19]F* NQI are well reproduced by the investigation using the IB and AB models. The second category of the systems investigated deals with the NQI and magnetic hyperfine interaction of [sup 63]Cu in La[sub 2]CuO[sub 4] and YBa[sub 2]Cu[sub 3]O[sub 6] as well as the NQI of [sup 139]La and [sup 135]Ba in the former and the latter compounds respectively. In the third category, the author investigates the possible stable sites of the Muon Spin Rotation ([mu]SR) probe atom, positive muon ([mu][sup +]) in La[sub 2]CuO[sub 4], and the hyperfine field (H[sub hyp]) at [mu][sup +] site in the antiferromagnetic phase of the system. The most stable [mu][sup +] site is at (0.121a, 0.0, 0.110c) of the tetragonal La[sub 2]CuO[sub 4] unit cell. The value of H[sub hyp] at this site is in reasonable order of magnitude with the observed one.« less
  • Using an envelope function model, the author has calculated the valence band structures in quantum wells and superlattices. It is found that the valence bands exhibit very complicated structures. With the newly devised method and the aid of the CRAY supercomputer, the author has been able to calculate the optical absorption spectra for a number of GaAsGa{sub 1-x}Al{sub x}As superlattices and quantum wells with the valence band mixing included. The results which feature the saddle point exciton resonances in superlattices are in good agreement with the experimental data. The continuum model (recently confirmed by microscopic calculations) shows that, for GaAs-AlAsmore » superlattices, there exist a number of interface and angle-dependent long-wavelength optical modes. To better understand these properties, the author developed a simple microscopic model which helps understand these novel features both qualitatively and quantitatively. This also enables one to obtain the phonon-polariton dispersion curves in superlattices with spatial dispersion included.« less
  • Optical and electronic properties of semiconductors heterostructures are analyzed, combining many-body and band structure engineering techniques. The Coulomb interaction is considered in different excitation regimes. For the low density excitonic limit, it is shown that superlattices can be modelled as 3D effective anisotropic media and the method is applied to the computation of exciton binding energies. In the high density regime, coupled band optical Bloch equations are obtained, combining Coulomb effects with the solutions of the Luttinger Hamiltonian, and the problem is solved in general under quasi-equilibrium conditions. Expressions for the band gap shift and the Coulomb enhancement in amore » Pade' approximation are obtained and solved in the context of a quasi-statically screened Coulomb interaction. The resulting equations are used to study the influence of band-structure and many-body effects in the gain and [alpha]-factor of both lattice-matched and strained quantum well lasers.« less
  • This dissertation utilizes optical spectroscopy in the study of electronic transitions in single crystals of three metal complexes. In Na[sub 3][Ho(C[sub 4]H[sub 4]O[sub 5])[sub 3]][center dot]2Na-ClO[sub 4][center dot]6H[sub 2]O (HoODA) and Cs[sub 2]Y[sub 1[minus]x[minus]y]Tb[sub x]Eu[sub y]Cl[sub 6], the transitions are intraconfigurational 4f-4f transitions of lanthanide ions. In Na[UO[sub 2](CH[sub 3]COO)[sub 3]], the transitions are between electronic states of the uranyl ion, UO[sup 2+][sub 2], which do not involve f orbitals. The HoODA study involved low-temperature measurements of absorption and circular dichroism spectra. The energy levels and line strengths were analyzed in terms of two parametric models. The parameters obtained weremore » used to simulate absorption and circular dichroism spectra, and were compared to the experimental spectra. The Cs[sub 2]NaY[sub 1[minus]x[minus]y]Tb[sub x]Eu[sub y]Cl[sub 6] study involved energy transfer from Tb[sup 3+] to Eu[sup 3+]. Decay kinetics of the [sup 5]D[sub 4] level of Tb[sup 3+] were measured and analyzed, and Tb[sup 3+]-Eu[sup 3+] interaction parameters were calculated from spectroscopic data. The Na[UO[sub 2](CH[sub 3]COO)[sub 3]] study involved the measurement of steady-state absorption and circular dichroism spectra and time-resolved and steady-state total luminescence and circularly polarized luminescence spectra at low temperatures. The first two projects (involving HoODA and Cs[sub 2]NaY[sub 1[minus]x[minus]y]Tb[sub x]Eu[sub y]Cl[sub 6]) are examples of two aspects of lanthanide spectroscopy: parametric analysis of detailed energy level structure and optical transition intensities, and the study of electronic energy-transfer processes. The third project is different because the electronic transitions studied are not f-f transitions. The study combines the experimental techniques used in the first two projects: steady-state absorption and emission measurements, and time-resolved emission measurements.« less