ZnSe及ZnSe/GaAs异质结构中压力导致的直接禁带向间接禁带的转变

用经验赝势方法计算了体ZnSe以及ZnSe/GaAs单异质结系统中ZnSe外延层г、X、L等特殊对称点导带底能量随压力的变化。结果表明，同Si、Ge、GaAs等半导体材料不同，ZnSe的X点导带底具有正的压力系数，但比г点的压力系数小，这是ZnSe材料以及ZnSe基异质结构材料发生直接禁带向间接禁带的转变时所需转变压力较大的根本原因。研究了ZnSe/GaAs异质结构中晶格失配造成的应变对外延层г、X、L对称点压力系数的影响，表明这种晶格失配造成的应变可以极大地减小ZnSe外延层材料由直接禁带向间接禁带的转变压力。     

纳米级自旋电子学材料取得重要进展

因为纳米级的自旋电子学器件需要在纳米尺度上仍能在较高温度下保持优异性能的高自旋极化率材料，故与半导体相容的半金属铁磁体近来受到高度重视．文章介绍作者在这个方向上研究工作的最新重要进展：通过大规模系统的高精度第一原理计算，作者发现三个3d过渡金属硫系化合物的闪锌矿相具有优异的半金属铁磁性，并且其结构性能适合做成具有足够厚度的薄膜或层状材料，便于应用于纳米级自旋电子学器件。     

What Is Its Real Existing Form?——Theoretical and Experimental Studies on 2-Mercaptobenzothiazole

1 INTRODUCTION The study of heterocyclic molecules with aroma- tic rings and their absorptions on metals is of con- siderable importance from both theoretical and te- chnological points of view. These molecules are in- teresting because of their applications as corrosion inhibitors and flotation collectors, and their abilities to form self-assembly layers[1]. 2-Mercaptobenzo- thiazole (C7H5NS2, in the following MBT) is an important heterocyclic molecule, which can be used as corrosion …     

Origin of the 420 nm Absorption Band and Effect of Doping Fluorine in PbWO4 Crystals

The electronic structures for three types of PbW04 (PWO) crystals, the perfect PWO, the PWO containing lead vacancy (PWO-Vpb) and fluorine doped PWO crystal (F^-：PWO), are systematically studied within the framework of density functional theory. The computational results show that the Pb 6s state situates below the valence band so that Pb^2 ions are unable to trap holes forming Pb^3 or Pb^4 to compensate for VPb^2-. The hole-trappers in PWO-Vpb are O^2- ions. Two of the longer-bond O^2- ions share a hole forming O2^3-, and four of the longer-bond oxygen ions trap two holes forming an associated color centre [O2^3--Vpb-O2^3-], which may be the origin of the 42Onto absorption band. It is also concluded that the doping of F^- would reduce the band gap and F^- ions substituting for O^2- can effectively restrict the formation of [O2^3--Vpb-O2^3-] and weaken the 42Onm absorption band and hence enhance the scintillation property of PWO.     

Structural and Electrical Characteristics of Pb（Zr0.53,Ti0.47）O3 Thin Films Deposited on Si （100） Substrates

Pb(Zr0.53, Ti0.47)O3 (PZT) films were directly deposited on Si substrates without a buffer layer by pulsed laser deposition. Only(110)-oriented PZT peaks (other than Si substrate peaks) were observed from the XRD data. The electrical properties of the PZT/Si capacitor were characterized in terms of both the capacitance versus voltage (C-V) and current versus voltage (I-V) measurements. The clockwise trace of the C-V curve shows ferroelectric polarization switching, as is expected. From the I-V curves, the Schottky emission and spacecharge-limited-current behaviour are found to be the mainly leakage current mechanism in a certain electric field range in the negative and positive bias, respectively.     

薄铝埋点等离子体K线光谱半定量诊断

高温等离子体系统中存在等离子体流体力学运动演化过程、离子的离化分布演化动力学过程、高剥离态离子谱发射过程及发射芬光辐射输运过程等，而且高温等离子体系统通常是非平衡系统，所以定量研究高温等离子体系统的发射X光谱和高温等离子体对X光的吸收是一个非常复杂的问题。为了模拟和解释实验测得的激光等离子体发射光谱，提出了一种薄埋点靶：直径为φ200μm厚度为0．1μm的铝点埋在20μm厚的CH膜底衬中，表面再覆盖0．1μm厚CH膜。     

模糊关系矩阵传递闭包的Warshall算法

通过对照关系的传递闭包和模糊关系的传递闭包，把求关系矩阵的传递闭包的算法完整地推广到模糊关系矩阵上。     

通用串行总线USB2．0规范的功能分析

本文对通用串行总线USB2．0的性能特点、拓扑结构、通用操作和USB设备驱动程序与Windows的接口进行分析。     

铁铝催化体系催化丙烯酸丁酯聚合

研究了Fe(acac)3-Al(i-Bu)3-8-羟基喹啉(acac=乙酰丙酮)催化体系催化丙烯酸丁酯(BA)聚合，考察了聚合规律，用凝胶渗透色谱研究了聚合物分子量和分子量分布．动力学研究表明聚合反应对单体浓度呈一级关系，表观活化能为13．9kJ／mol．