低温制备微晶硅薄膜生长机制的研究

采用热丝化学气相沉积技术制备了一系列处于不同生长阶段的薄膜样品，用原子力显微镜系 统地研究生长在单晶硅衬底和玻璃衬底上薄膜表面形貌的演化.按照分形理论分析得到：在 玻璃衬底上的硅薄膜以零扩散随机生长模式生长；而在单晶硅衬底上，薄膜早期以有限扩散 生长模式生长，当膜厚超过某一临界厚度时转变为零扩散随机生长模式.岛面密度与膜厚的 依赖关系表明，在临界厚度时硅衬底和玻璃衬底上的岛面密度均出现了极大值.Raman谱的测 量证实，玻璃衬底上薄膜临界厚度与非晶/微晶相变之间存在密切的关系.不同的衬底材料直 接影响反应 关键词： 生长机制 微晶硅薄膜 表面形貌 热丝化学气相沉积     

基于ElGamal公钥体制的数字签名研究

利用有向签名和盲签名相结合的方法，在ElGamal公钥体制的基础上提出了一种新型数字签名方案，并对其安全性进行了分析，同时依据初等数论知识从理论上证明了该方案中的可行性，并通过实例验证，在真正意义上实现了电子交易中的匿句特性，并达到了安全性和可操作性的实用要求。     

Fabrication of c-Si：H（p）/c-Si（n） Heterojunction Solar Cells with Microcrystalline Emitters

The p-type microcrystalline silicon （μc-Si：H） on n-type crystalline silicon （c-Si） heterojunction solar cells is fabricated by radio-frequency plasma enhanced chemical vapour deposition （rf-PECVD）. The effect of the μc- Si：Hp-layers on the performance of the heterojunction solar cells is investigated. Optimum μc-Si：H p-layer is obtained with hydrogen dil u tion ratio of 99.65 %, rf-power of 0. 08 W/cm^2 , gas phase doping ratio of 0. 125 %, and the p-layer thickness of 15nm. We fabricate μc-Si：H（p）/c-Si（n） heterojunction solar cells without texturing and obtained an efficiency of 13.4%. The comparisons of the solar-cell performances using different surface passivation techniques are discussed.     

固态量子计算的若干重要物理问题研究

量子计算机拥有比经典计算机更为强大的计算能力．人们普遍认为量子计算机最终将会在固态系统中实现．文章介绍了一些有关固态量子计算的研究进展，其中包括超导电荷量子比特方案、几何量子计算、量子点量子比特及量子计算若干基本问题研究．最后给出了固态量子计算的发展趋势．     

EFFECTIVE-MASS THEORY FOR InAs/GaAs STRAINED SUPERLATTICES

By using the recently developed exact effective-mass envelope function theory, the electronic structures of InAs/GaAs strained superlattices grown on GaAs (100) oriented substrates are studied. The electron and hole subband structures, distribution of electrons and holes along the growth direction, optical transition matrix elements, exciton states, and absorption spectra are calculated. In our calculations, the effects due to the different effective masses of electrons and holes in different materials and the strain are included. Our theoretical results are in agreement with the available experimental data.     

Population inversion study of GaAs/AlGaAs three-quantum-well quantum cascade structures

A population inversion study of GaAs/AlxGa1-x As three-quantum-well quantum cascade structures is presented. We derive the population inversion condition (PIC) of the active region (AR) and discuss the PICs on different structures by changing structural parameters such as the widths of quantum wells or barriers in the AR. For some instances, the PIC can be simplified and is proportional to the spontaneous emission lifetime between the second and the first excited states, whereas some other instances imply that the PIC is proportional to the state lifetime of the second excited state.     

丙烯水合醚化反应过程中丙酮生成机理的研究

 在与色－质联用仪相连的微反装置上，考察了Hβ沸石及改性的\r\nHβ沸石催化剂上丙烯水合醚化及异丙醇脱水的反应行为．丙烯水合醚\r\n化反应中有副产物丙酮生成，而异丙醇单独进料时产物中没有发现丙酮\r\n的生成．这表明丙酮并不是异丙醇氧化脱氢的结果，而是一个应予重视\r\n的不利于丙烯水合醚化的副反应．用同位素示踪反应对丙酮的生成机理\r\n进行了探讨，为研制抑制这一副反应的新催化剂提供了参考依据．     

亚强非局域介质中的超高斯空间光孤子族研究

研究了亚强非局域介质中超高斯光束的传播特性.运用变分法,对任意实对称响应函数泰勒级数展开取至四阶,得到了1+1维亚强非局域非线性介质中光束传输的超高斯光束的近似分析解.分析结果表明：束宽解是椭圆雅可比双周期函数,相移、空间啁啾以及临界输入功率都正比于超高斯光束的阶数.提出了超高斯空间光孤子族模型和准方波形空间光孤子的实现可能性.     

Effective-mass theory for coupled quantum dots grown on （11N）-oriented substrates

The electronic structures of coupled quantum dots grown on （11N）-oriented substrates are studied in the framework of effective-mass envelope-function theory. The results show that the all-hole subbands have the smallest widths and the optical properties are best for the （113）, （114）, and （115） growth directions. Our theoretical results agree with the available experimental data. Our calculated results are useful for the application of coupled quantum dots in photoelectric devices.     

Magnetization of two-dimensional heavy holes with boundaries in a perpendicular magnetic field

The magnetisation of heavy holes in III--V semiconductor quantum wells with Rashba spin-orbit coupling (SOC) in an external perpendicular magnetic field is studied theoretically. We concentrate on the effects on the magnetisation induced by the system boundary, the Rashba SOC and the temperature. It is found that the sawtooth-like de Haas--van Alphen (dHvA) oscillations of the magnetisation will change dramatically in the presence of such three factors. Especially, the effects of the edge states and Rashba SOC on the magnetisation are more evident when the magnetic field is smaller. The oscillation center will shift when the boundary effect is considered and the Rashba SOC will bring beating patterns to the dHvA oscillations. These effects on the dHvA oscillations are preferably observed at low temperatures. With increasing temperature, the dHvA oscillations turn to be blurred and eventually disappear.