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101.
Electronic properties of both Pb and S vacancy defects in PbS(1^-00) have been studied using the first-principles density functional theory (DFT) calculations with the plane-wave pseudopotentials. It is found that the density of states (DOS) near the top of the valence band and the bottom of the conduction band is significantly modified by these defects. Our calculation indicates that in the case of S vacancy defects the Fermi energy shifts to the conduction band making it as an n-type PbS (donor). However, in the case of Pb vacancy, because of the appreciable change of the DOS, the system acts as a p-type PbS (accepter). In addition, the structural relaxation shows that the defect leads to outward relaxation of the nearest-neighbouring atoms and inward relaxation of the next-nearest neighbouring atoms. 相似文献
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We perform the ab initio calculation for obtaining the density of states and magnetic properties of ZrFe2 Laves phase compound based on the method of augmented plane waves plus local orbital The results indicate that the ferromagnetic state is more stable than the paramagnetic one, but with a slightly larger volume. The 3d - 4d exchange interactions between Fe and Zr electrons lead to the antiparallel coupling for Fe 3d and Zr 4d states, which is responsible for the ferrimagnetic ordering of the compound. The resulting magnetic moment of about 1.98μB for Fe is spatially localized near the Fe site, while around Zr a small but extended negative spin states causes a moment of about -0.44 μB. Moreover, the resulting magnetic moments with the generalized gradient approximation are more consistent with experimental values than that of the local-spin density approximation. 相似文献
106.
Growth of Semi-Insulating GaN Using N2 as Nucleation Layer Carrier Gas Combining with an Optimized Annealing Time 下载免费PDF全文
Semi-insulating (SI) GaN is grown using N2 as the nucleation layer (NL) carrier gas combined with an optimized annealing time by metalorganic chemical vapour deposition. Influence of using 1-12 and N2 as the NL carrier gas is investigated in our experiment. It is found that the sheet resistance of unintentionally doped GaN can be increased from 10^4 Ω/sq to 10^10 Ω/sq by changing the NL carrier gas from 1-12 to N2 while keeping the other growth parameters to be constant, however crystal quality and roughness of the tilm are degraded unambiguously. This situation can be improved by optimizing the NL annealing time. The high resistance of GaN grown on NL using N2 as the carrier gas is due to higher density of threading dislocations caused by the higher density of nucleation islands and small statistic diameter grain compared to the one using 1-12 as carrier gas. Annealing the NL for an optimized annealing time can decrease the density of threading dislocation and improve the tilm roughness and interface of AlGaN/GaN without degrading the sheet resistance of as-grown GaN signiticantly. High-quality SI GaN is grown after optimizing the annealing time, and AlGaN/GaN high electron mobility transistors are also prepared. 相似文献
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应用 δ2 —加速技巧 ,对 Broyden的计算格式作了修正 .提出了一种新的修正的计算格式 ,给出了计算的步骤及数值例子 . 相似文献
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具有可选服务的M/M/l排队模型的豫解集 总被引:1,自引:0,他引:1
邢喜民 《新疆大学学报(理工版)》2008,25(4)
运用线性算子及其共轭算子的谱之间的关系,研究具有可选服务的M/M/1排队模型主算子的豫解集,并得到在虚轴上除了零外其它所有点都属于该算子的豫解集. 相似文献