Electronic and Optical Properties of GaN / AlN Multiple Quantum Wells under Static External Magnetic Field

In this work, we have investigated the effect of an external magnetic field and, for the first time, number of wells with constant total effective length to study the degeneracy in electronic energy levels. We have used constant total effective length because it is technologically important. Then we have tried to remove the n-fold degeneracy of the n-well multiple quantum well by means of the external magnetic field but the two-fold degeneracy was remain and not removed. Finally, the effect of the external magnetic field on the number of bound states and the situation of unchanging absorption coefficient in a wide magnetic field interval are also investigated. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3195

Two Dimensional Coulomb Potential of Confined Excitons in Quantum Well Structures

In this study, we have investigated an exciton confined in a single quantum well. For the first time, we have compared the different methods of approximating the effective two dimensional Coulomb potentials which had been previously reported in the literatures. The effect of different previously introduced trial wave functions on the exciton binding energy is also investigated. In order to have a consistent and stable calculation we have tried to find the true region of variations for free parameters of these trial wave functions. Effects of the barrier thickness and doping fraction are also investigated. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3026

Efficacy of CIDR, fluogestone acetate sponges and cloprostenol for estrous synchronization of Nadooshani goats during the breeding season

Summary The objective of this study was to evaluate three methods of estrous synchronization, viz. controlled internal drug releasing device (CIDR), intravaginal sponges impregnated with fluogestone acetate (FGA), and cloprostenol (Estrumate; an analogue of prostaglandin F 2 α) in Nadooshani goats of Yazd province, Iran. The estrous synchronized does (n = 30 to 33 per treatment), after heat detection, were artificially inseminated (once) with diluted semen of fertile bucks. Pregnancy was determined by measuring blood serum progesterone levels on day 21 after insemination, followed by ultrasonography at mid-gestation. No significant difference was observed for the interval between the end of the synchronization protocol and the standing heat amongst treatments (range: 23 to 35 hrs). There was no significant difference in the interval between the time of standing heat and insemination among treatments (range: 15 to 27 hrs). Blood serum progesterone levels (overall mean: 4.80 ± 0.41 ng/ml; SEM), litter size (overall mean: 1.32 ± 0.05; SEM), non-return rate to estrus and the kidding rate were not significantly affected by the synchronization methods. Serum progesterone levels were significantly lower (P<0.01) in does that returned to estrus after artificial insemination (AI). Prolificacy and fecundity were not significantly affected by the synchronization methods; however, cloprostenol method was found to be more convenient and economical under the conditions of this experiment

Calculation of Elecron Mobility in WZ-AlN and Electric Field 1

In this work the electron mobility of AlN Wurtzite and AlN Zincblende semiconductor compounds were calculated using iterative method in range of 100-600 K. We compare polar optic phonon scattering, deformation-potential acoustic phonon scattering, piezoelectric scattering and impurity scattering mechanisms. Boltzmann transport equation was solved using iterative method. In addition, we took into account the mixing of wave functions and electron screening and we investigated temperature dependence of mobility of the given compound

Hydrogen-induced improvements in optical quality of GaNAs alloys

Strong suppression of potential fluctuations in the band edges of GaNAs alloys due to postgrowth hydrogen treatment, which is accompanied by a reopening of the alloy band gap, is revealed from temperature-dependent photoluminescence (PL) and PL excitation measurements. The effect likely indicates preferential trapping of hydrogen near the lattice sites with the highest nitrogen content. A remarkable improvement in the radiative efficiency of the alloys at room temperature is also demonstrated and is ascribed to efficient hydrogen passivation of competing nonradiative centers. (C) 2003 American Institute of Physics

Unusual effects of hydrogen on electronic and lattice properties of GaNP alloys

Hydrogen incorporation is shown to cause passivation of various N-related localized states and partial neutralization of N-induced changes in the electronic structure of the GaN(x)P(1-x) alloys with x < 0.008. According to the performed X-ray diffraction measurements, the hydrogenation is also found to cause strong expansion of the GaNP lattice which even changes from a tensile strain in the as-grown GaNP epilayers to a compressive strain in the post-hydrogenated structures with the highest H concentration. By comparing results obtained using two types of hydrogen treatments, i.e. by implantation from a Kaufman source and by using a remote dc H plasma, the observed changes are shown to be inherent to H due to its efficient complexing with N atoms, whereas possible effects of implantation damage are only marginal. (c) 2005 Elsevier B.V. All rights reserved