ELECTRON-STATES OF A VACANCY IN THE CORE OF THE 90-DEGREES PARTIAL DISLOCATION IN SILICON

An LCAO scheme (linear combination of atomic orbitals) taking into account ten atomic orbitals (s-, p-, and d-type) is used to calculate the electronic structure of a vacancy present in the core of the reconstructed 90 degrees partial dislocation in silicon. The levels in the band gap are extracted using Lanczos' algorithm and a continued fraction representation of the local density of states. The three-fold degenerate stale of the ideal vacancy is split into three levels with energies 0.26, 1.1, and 1.9 eV measured from the valence band edge.

有机／无机杂化SiO_2／Si光波导薄膜的制备及表征

采用有机／无机杂化溶胶-凝胶（sol-gel）法制备了SiO_2光波导薄膜材料。采用甲基丙烯酰氧丙基三甲氧基硅烷（MAPTMS）作为反应先躯体，四丙氧基锆（ZPO）作为调节折射率的材料，正丙醇（n-propyl alcohol）为溶剂，利用旋涂方法在Si基片上成膜，采取低温长时间、高温短时间的热处理方式，制备出无龟裂薄膜。分别采用棱镜耦合仪和原子力显微镜（AFM）研究了不同溶剂量和不同ZPO量情况下，薄膜的折射率、厚度以及表面形貌变化情况。研究结果表明

功率型GaN基LED静电保护方法研究

介绍了几种常用的GaN基大功率白光发光二极管（LED）静电保护的方法，分析了GaN基大功率白光LED静电损伤的机理，并在此基础上，提出了改善GaN基大功率白光LED的抗静电损伤的途径与方法。

Comparative study of the mode-locking of Nd:GdVO4 and Nd:YAG lasers with semiconductor saturable absorber mirrors

Stable continuous-wave passive mode-locking of diode-end-pumped Nd:GdVO4 and Nd:YAG lasers withsemiconductor saturable absorber mirrors (SESAMs) are reported. The comparative study shows that theNd:GdVO4 crystal is efficient to decrease the Q-switched mode-locking tendency, and easier to continuous-wave (CW) mode lock than Nd:YAG.

GaAs／Si／AlAs异质结不同生长温度Si夹层分布的CV实验研究

用MBE生长设备制造了GaAs/Si/AlAs异质结，通过CV法研究了异质结的带阶和GaAs层在不同温度下生长对0．5分子层Si夹层的影响，得到Si夹层的空间分布随GaAs层生长温度的升高而由局域变为弥散的温度效应。

InGaAs/GaAs垂直对准量子点超晶格的正入射红外吸收

利用分子束外延技术,生长了30周期的InGaAs/GaAs量子点超晶格。透射电镜表明各层量子点沿生长方向呈现很好的垂直对准。红外吸收测试观察到明显的垂直入射红外吸收,吸收范围在8.5 μm～10.4 μm之间,峰值波长为9.9 μm,第一次实现了响应8 μm～12 μm大气窗口的量子点的垂直入射红外吸收,这一结果预示了量子点超晶格结构在红外探测领域的潜在应用。

不同温度下快速热退火对SiGe量子阱光致发光谱的影响

对GS-MBE生长的Si/SiGe/Si量子阱结构用快速热退火(RTA)方法进行处理，研究了其在低温下的光致发光(PL)特性。发现存在一个最佳退火温度范围，使得PL谱的发光得到改善。随着退火温度的继续提高，PL谱线发生兰移，发光强度下降。认为这种趋势是由内部缺陷和位错以及Si/SiGe/Si量子阱结构在退火过程中相应的变化所导致。辅助的缺陷显微观察证实了此结论。

激光衰减法测量固体火箭发动机尾流粒子参数

为了测量某固体火箭发动机尾流粒子参数,设计了基于激光衰减法的实验系统,并在发动机试车中采取了消除尾流辐射干扰的措施.将实验结果与参考文献的激光衰减法测量结果进行了比较,结果一致,表明所获得光强衰减信号和测量结果是可信的.在发动机燃烧室压强为9.5 MPa时,利用激光衰减方法测量喷管出口的粒子尺度d32=0.9μm,实验数据误差为20%

Effect of Nozzle Temperature on the Performance of a 1 kW H2-N2 Arcjet Thruster

A 1 kW-class arcjet thruster was ¯red in a vacuum chamber at a pressure of 18 Pa. A gas mixture of H2 : N2 = 2.8 : 1.5 in volume at a total °ow rate of 4.3 slm was used as the propellant with an input power ¯xed at 860 W. The time-dependent thrust, nozzle temperature and inlet pressure of the propellant were measured simultaneously. Results showed that with the increase in nozzle temperature the thrust decreased and various losses increased. The physical mechanisms involved in these effects are discussed.