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Abstract: The model for amorphous semiconductor InSb (a-InSb) was constructed through the first principles calculations, based on the idea of “continuous random networks” (CRN). The results of structural parameters for a-InSb are in agreement with the available data both theoretically and experimentally. The structure of a-InSb is almost tetrahedrally bonded with a perfect average coordination number of four. Due to the influence of the disorders, the density of states for a-InSb has the smearing structure in contrast to crystalline InSb (c-InSb). As a consequence of the induction of disorders, modification phenomena occur at the band edge of a-InSb in contrast to that of c-InSb. [Copyright &y& Elsevier]

The effect of Nb doping of oxide perovskite SrTiO3 on the electronic properties is studied by semirelativistic linear muffin-tin orbital method with atomic sphere approximation (LMTO-ASA). The computational lattice constants are in good agreement with experimental data. The Fermi level of SrTi1−xNbxO3 with x⩾0.125 moves into the bottom of conduction band and the system shows metallic behavior. Due to the appearance of the charge impurity potential from Nb doping, there is a large distortion on the top of valence band for SrTi1−xNbxO3 with 0.125⩽x⩽0.25. The distortion becomes weak with x=0.5 because of the carriers screening effect. Our computational results also show that the Nb doping effect on the electronic structure of SrTi1−xNbxO3 cannot be described within a simple rigid-band model well. [Copyright &y& Elsevier]

Abstract: Using first-principles method we studied the compensation mechanism of As donor in Hg1− x Cd x Te based on the model Berding et al. (1998, 1999) of pair. We show that the binding of AsHg and results from donor-acceptor coupling, and the compensation of As donor can be clearly explained in terms of electronic deactivation by . The pairing physics derived from this study confirm the available theoretical and experimental results. [ABSTRACT FROM AUTHOR]

Using first-principles calculations, we investigate the atomic and electronic structure of La 3 GaGe 5 O 16 and its oxygen vacancies with an aim to evaluate the potential of La 3 GaGe 5 O 16 as a new persistent phosphor. We find that oxygen vacancies prefer the bridging sites within [Ge m O n ] groups over the bridging sites between groups. Oxygen vacancies are found to act as an electron trap center and their trap states are of conduction band character of the host. By comparison with other excellent persistent phosphors, we suggest that La 3 GaGe 5 O 16 cannot emerge as an efficient persistent phosphor, and the most likely cause is the formation of ring structure and rather localized conduction band of the host. The ring structure makes most of oxygen atoms structurally inactive and the localized conduction band results in low concentration of trapping electrons. Our results thus provide fundamental explanations for the inferior persistent performance of La 3 GaGe 5 O 16 phosphor. [ABSTRACT FROM AUTHOR]

Abstract: Using first-principles methods, we have investigated structural and electronic properties of substitutional arsenic donor (AsHg), mercury vacancies (V Hg), and their complexes in arsenic doping of HgCdTe. The role of V Hg in arsenic activation has also been discussed. Counterintuitively, we find that AsHg and V Hg is a single donor and a single acceptor, respectively. The unpaired electron of AsHg makes it act as a nucleation center, driving arsenic interstitials into clusters, which is predicted as a potential candidate for arsenic deactivation. V Hg, exhibiting comparable formation energy with the AsHg donor as well as a shallow acceptor level, is a dominant compensating acceptor in as-grown materials. Coulomb interaction allows AsHg to bind at most one or two V Hg. The resulting complexes behave as compensating acceptors at low temperature. The model outlined for carrier compensation in arsenic-doped HgCdTe contacts well with experimental observations in arsenic activation. [Copyright &y& Elsevier]