Browsing by Subject "Semiconductors -- Defects"
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Item Chemical trends for deep levels associated with vacancy-impurity complexes in semiconductors(Texas Tech University, 1986-05) Shen, Yu-tangBeginning with the theory of deep traps due to vacancy-impurity pairs, we have developed a theory of deep levels associated with vacancy-impurity complexes in zincblende hosts. We consider triplet complexes which consist of a vacancy that is a nearest-neighbor to two identical, substitutional impurities. Such defects are thought to play an important role in recombination processes in device materials. On the basis of this theory, the chemical trends in such deep levels are predicted for 12 semiconductors and for the semiconductor alloy GaAsi-xPx* These predictions show that a triplet complex may have deep levels which are very different from those of either the isolated impurity or the vacancy-impurity pair. For example, complexing with a second impurity can produce deep levels at energies where neither the pair nor the isolated impurity produce any. Examples of such effects are discussed for GaP and GaAs1-xPx.Item Deep level transient spectroscopy and uniaxial stress system(Texas Tech University, 1990-12) Yang, ShilianDeep level transient spectroscopy (DLTS) combined with uniaxial stress will not only determine the energy level of a defect center in semiconductor but also tell its symmetry, which is very important for identifying the structure of a defect center. As a thesis for my Master's of Science Degree, this report explains the theories of DLTS and uniaxial stress, our experimental system and some initial results obtained from this system.Item Effects of lattice relaxation on deep levels in semiconductors(Texas Tech University, 1991-05) Li, Wei-gang.Item Oxygen thermal donor formation in Cz-silicon(Texas Tech University, 1990-12) Jones, Bobby DaleDeep level transient spectroscopy has been used to study the kinetics of oxygen in Czochralski (CZ) grown silicon as a function of annealing time at 450°C. Specifically, the concentrations of the E^ - 0.15 eV and the E^ - 0.07 eV thermal donors have been analyzed. Changes in the energy levels of the thermal donors as a function of anneal time has also been observed. This may be due to previously unknown formative abilities of the thermal donor complex as oxygen atoms accrete to the thermal donor core. Investigations also reveal that these two thermal donors' concentrations grow at different rates. AIso, the concentration of the E(0.15) thermal donor is consistently greater than or equal to the concentration of the E(0.07) thermal donor. However, total thermal donor concentrations are still consistent with previous data obtained by C-V me as ureme nt s.Item Simulation and estimation of copper electroplating using level set methods and image processing techniques(Texas Tech University, 2002-05) Carr, Nan ZhouNot available.Item Structural and vibrational properties of N, N pairs, and [N,H] complexes in silicon(Texas Tech University, 2004-08) McAfee, Jason LFirst-principles molecular-dynamics simulations are used to predict the structures and binding energies of interstitial nitrogen (Ni), substitutional nitrogen (Ng), the Njself- interstitial complex, the {Ni,Ni}, {Ni,Ns} = {N2,V}, and {Ng, N J = {N2,V2} pairs (V is the vacancy). The interactions of N with H in Si are studied and the properties of several {N, H} complexes predicted. The dynamical matrices yield many new local and pseudo-locfil vibrational modes associated with the impurities and their Si nearest-neighbors. The unidentified (N, H}-related infra-red absorption line reported by Pajot et al. is assigned to the {Ng, H} complex.Item Theory of alloy broadening of deep electronic energy levels in ternary semiconductor alloys(Texas Tech University, 1986-05) Ford, William CliffordThe effects of alloy disorder on deep electronic levels produced by point defects in some of the technologically important ternary semiconductor alloys are investigated using the embedded cluster method and the theory of deep levels. Deep levels produced by defects both with nearest-neighbor and with second-neighbor alloy disorder are studied. The alloy host is treated by embedding an ensemble of clusters each of which contains five atoms (for nearest-neighbor disorder) or seventeen atoms (for second-neighbor disorder) in a virtual crystal approximation effective medium. The theory of deep levels is then used to find the deep levels in the bandgap of the host material for each cluster configuration when the central atom is replaced by a point defect. Results are presented for the inhomogenously broadened deep level spectra due to substitutional impurities on the anion site in AlxGa-x.As, Hg1-xCdxTe, and GaAS1-x, Px as well as due to the ideal As vacancy in AlxGa1-xAs. Specifically, the alloy composition dependences of the first moment, the component deep levels, and the linewidths of the spectra associated with these defects are presented.