自发发射因子在外腔半导体激光器的模式选择和线宽压缩过程中的作用

本文提出并论证外腔模式自发发射因子急剧减小使模式选择所需的增益差和光场相位噪声皆急剧减小是外腔半导体激光器具有优异的纵模选择和线宽压缩性能同时又具有严重不稳定性的统一的关键性物理根源。     

采用DBR LD的正弦相位调制激光干涉仪

分析影响正弦相位调制半导体激光干涉仪测量精度和系统分辨力的因素,提出了用分布布拉格反射半导体激光器DBR LD实现高分辨力亚纳米精度测量的方案。理论计算表明,DBR LD的波长连续调制深度比F-P腔LD高一个量级。指出邮于DBR LD的特殊结构可通过简单的反馈回路稳定输出光功率,有效地避免了光强波动对测量精度提高的限制。     

Hydrogen in semiconductors

Hydrogen in crystalline semiconductors has become a recent curiosity because of its high diffusivity and strong chemical activity in such materials. In contrast to the proton motion in ionic materials which gives rise to an enhanced conductivity, hydrogen in electronic materials interact with structural disorders and chemical impurities to control the electronic flow. Deep gap states in crystalline semiconductors due to various disorders such as surface/interface, grain boundaries, dislocations, irradiation and implantation damage etc. have been removed due to hydrogen bondings. Hydrogen incorporation is done by plasma and direct ion beam hydrogenation methods, implantation technique and by a novel technique of damage free introduction. The most studied materials are silicon and gallium arsenide.I - V,C - V, DLTS and IR studies have been carried out on hydrogenated semiconductors to characterize the electronic flow, gap states and the nature of chemical bonds. Improvement in ideality factors of diodes, reduction in free carrier concentration, removal or reduction of deep states and appearance of new bondings such as Si-H, P-H, B-H etc. have been observed from various techniques. The present paper reviews the various features of hydrogenation studies in crystalline silicon and gallium arsenide and highlights our results of hydrogenation studies on Pd/semiconductor devices.     

深能级中心的电场增强载流子产生效应

本文研究了半导体表面空间电荷区中的深能级中心的电场增强载流子产生效应;指出应全面考虑库仑发射和非库仑发射对载流于产生率的影响;给出了相应的产生率计算公式。对计算机计算结果的分析表明,以往的只考虑库仑发射的模型过于简单,本文理论可以较满意地解释有关的实验结果。     

Gap－LPE掺S浓度的控制及对发光效率的影响

报道了具有双ｎ型结构的ＧａＰ绿色发光二极管在汽相掺杂、液相外延过程中，对硫（Ｓ）掺杂浓度的控制和监测方法，并研究了掺Ｓ浓度对发光效率的影响。     

基于532nm半导体激光器的远距离传输高精度准直系统设计

半导体激光器在军事、工业、医学等许多方面有着重要的应用前景,但由于半导体激光器输出光束具有较大的发散角,因而在几乎所有要求较高的应用领域中,其输出光束都必须通过特殊的光学系统进行准直。扩束镜因其结构简单、材料便宜以及加工容易而在半导体激光束准直领域获得较多的应用。     

含掺杂的金刚石

含Ⅲ族与Ⅴ族元素掺杂的金刚石是宽禁带的半导体材料，同时具有优异的物理化学特性，在电子器件与光电子器件方面的应用具有极大潜力，成为近几年来国内外研究的热点之一。本文介绍了目前常用的掺杂方法、技术水平及金刚石半导体的应用前景。     

Suppression of gold nanoparticle agglomeration and its separation via nylon membranes

Use of ultraporous nylon membrane is one of the most widely employed techniques for removal of hard and soft nanoparticles in the semiconductor industry,and the accurate determination of membrane pore size is necessary in order to avoid manufacturing defects caused by contamination.The gold nanoparticle has several benefits for the evaluation of polymeric membranes;however,the nanoparticles agglomerate easily on the nylon membrane and make it difficult to evaluate the membrane precisely.The properties of 2-amino-2-hydroxymethyl-1,3-propanediol (ADP) ligand in gold nanoparticle solution were systematically investigated,and ADP was utilized for improved evaluation of the nylon membranes.Nylon membrane used in this study was prepared by phase inversion techniques.Ultrathin dense layer on top of the membrane surface and Darcy structures in the microporous membrane support were observed.The gold particle rejection was carried out at various pH values from 4 to 14 and higher rejection was observed at pH 4 and 8.The suppression of gold colloid agglomeration using ADP and monodispersity of gold colloids was also analyzed by confocal laser scanning microscopy (CLSM),transmission electron microscopy (TEM),and scanning electron microscopy (SEM).van der Waals interaction energy of the particles was reduced in the addition of ADP.The presence ofADP ligand in the gold solutions prevented the agglomeration of gold nanoparticles and reduced the adsorption of the particles on the nylon membrane surface,leading to precise evaluation of membrane pore sizes.     

Formation and characterization of p-type semiconductor CuCrO2 thin films prepared by a sol–gel method

This study adopted the sol–gel method to synthesize p-type semiconductor CuCrO₂ films and analyzed the effects of an annealing treatment, under a controlled argon atmosphere by changing the temperature and time, on the phase transformation, micro- and nano-structure, composition, and semiconductor properties of thin films. In the Cu–Cr–O phase transformation system, CuO, Cr₂O₃, and CuCr₂O₄ were the intermediate phases of the reaction for forming CuCrO₂: in the metastable state reaction process, the composite phases changed into a single phase, CuCrO₂; in the stable-state reaction process of CuCrO₂, carbon elements of precursors were released and eliminated; and finally the optoelectronic properties of the CuCrO₂ thin film were adjusted and changed. The CuCrO₂ thin film possessed cell- and polygon-like shaped microstructures. The carbon content in the CuCrO₂ film decreased, so the copper, chromium, and oxygen contents increased accordingly. The optical band gap of CuCrO₂ thin film increased from 2.81 eV to 3.05 eV, while the resistivity decreased. The nanoscale crystal was identified which also of the delafossite CuCrO₂ structure. Using the sol–gel method to prepare the CuCrO₂ thin films, an appropriate annealing temperature and time were helpful in forming the single-phase CuCrO₂; the decrease of precursor elements in the thin film could enhance the band gap and the conductivity of the material.     

Low-temperature synthesis and optical properties of wurtzite ZnS nanowires

Single-crystal wurtzite ZnS nanowires have been synthesized via a facile solution route with polyethylene glycol-400 as inducing template at low temperature (170 °C). The as-prepared products have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and energy dispersive X-ray analysis (EDX). Raman and photoluminescence spectrum (PL) were used to investigate the optical properties of ZnS nanowires. The strong emission peak centered at 322 nm in PL spectrum could be attributed to the band to band transitions.