掺杂浓度对p-GaAs的带隙变窄的影响

用光致荧光的方法对分子束外延生长的(110)方向的掺Be的GaAs带隙变窄随掺杂浓度的变化进行研究。结果表明:对于P-GaAs,带隙变窄主要是价带上移造成的,杂质能级(带)相对导带的位置不变。因此,电离能随着掺杂浓度的增加而减小。     

氮化镓基发光二极管产业化中的材料物理问题

第三代半导体氮化镓化合物半导体已成为蓝光发光二极管的主流材料，国际上的产业化已成规模，国内也有多家处于中试阶段，由于氮化镓基材料中有如此多的问题没有解决，材料制备设备，器件工艺也极需改进及优化，这既给了中国科研人员及工程技术人员一个机遇，也使他们面临着严峻的挑战。     

一种简单高效的制备硅纳米孔阵结构的方法

本文介绍了一种简单高效的制备硅纳米孔阵结构的方法. 利用激光干涉光刻技术, 结合干法和湿法刻蚀工艺, 直接将光刻胶点阵刻蚀为硅纳米孔阵结构, 省去了图形反转工艺中的金属蒸镀和光刻胶剥离等必要步骤, 在2英寸的硅 (001) 衬底上制备了高度有序的二维纳米孔阵结构. 利用干法刻蚀产生的氟碳有机聚合物作为湿法刻蚀的掩膜, 以及在干法刻蚀时对样品进行轻微的过刻蚀, 使SiO₂点阵图形下形成一层很薄的硅台面, 是本方法的两个关键工艺步骤. 扫描电子显微镜图片结果表明制备的孔阵图形大小均匀, 尺寸可控, 孔阵周期为450 nm, 方孔大小为200–280 nm. 关键词： 激光干涉光刻 纳米阵列 刻蚀 氟碳有机聚合物     

分子束外延调制掺杂结构的低温光致荧光

本文报道了分子束外延调制掺杂GaAs/N-AIGaAs二维电子气材料的低温光致荧光结果。实验表明,光致荧光谱分析可以作为二维电子气材料的质量诊断技术,由光致荧光谱得到的质量评价与材料的电学性能恰相对应,这就为改进分子束外延工艺提供了依据。 关键词：     

Dislocation Reduction Mechanisms in Gallium Nitride Films Grown by Canti-Bridge Epitaxy Method

By using the special maskless V-grooved c-plane sapphire as the substrate, we previously developed a novel GaN LEO method, or the so-called canti-bridge epitaxy （CBE）, and consequently wing-tilt-free GaN films were obtained with low dislocation densities, with which all the conventional difficulties can be overcome [J. Vacuum Sci. Technol. B 23 （2005） 2476]. Here the evolution manner of dlslocations in the CBE GaN films is investigated using transmission electron microscopy. The mechanisms of dislocation reduction are discussed. Dislocation behaviour is found to be similar to that in the conventional LEO GaN films except the enhanced dislocation-combination at the coalescence boundary that is a major dislocation-reduction mechanism for the bent horizontal-propagating dislocations in the CBE GaN films. The enhancement of this dislocation-combination probability is believed to result from the inclined shape and the undulate morphology of the sidewalls, which can be readily obtained in a wide range of applicable film-growth conditions during the GaN CBE process. Further development of the GaN CBE method and better crystal-quality of the GaN film both are expected.     

Si Ge量子阱和超晶格的光发射

系统地介绍了近几年来国内外对ＳｉＧｅ量子阱及短周期超晶格光发射的研究现状。由于Ｓｉ，Ｇｅ材料及器件在微电子学领域内的无可比拟的优越性，所以，超过９０％的芯片技术是Ｓｉ基的，然而，由于Ｓｉ，Ｇｅ是间接带隙，载流子跃迁几率小，其光电应用受到很大的限制，为此，人们作出了不懈的努力，并取得了可喜的进展。     

Growth, Antimony Incorporation Behaviour and Beryllium Doping of GaAs1-ySby Grown on GaAs by Molecular Beam Epitaxy

A series of GaAs1-ySby epilayers are grown on GaAs substrates under antimony compositions of samples with beryllium doping are obtained different growth conditions. Different A non-equilibrium thermodynamics model is used to calibrate and fit the Sb composition. Activation energy of 0.37 eV for the dissociation process of Sb4 molecules is obtained. Carrier mobility and concentration of samples are influenced by the Sb composition. Quasi-qualitative analysis of mobility is used to explain the relations among Sb composition, carrier mobility and concentration. High resolution x-ray diffraction （HRXRD） rocking curves and Hall effects measurements are used to determine the crystal quality, carrier mobility and concentration.     

fT为13.5?GHz的平面结构SiGe异质结双极晶体管的研制

利用多晶硅发射极技术与分子束外延生长SiGe基区技术相结合,研制成适于集成的平面结构、发射结面积为3?μm×8?μm的SiGe异质结双极晶体管(HBT)。室温下该晶体管的直流电流增益β为30到50,基极开路下,收集极-发射极反向击穿电压BVCEO为5?V,晶体管的截止频率fT为13.5?GHz。     

Luminescent Characteristics of Near Ultraviolet InGaN/GaN MQWs Grown on Grooved Sapphire Substrates Fabricated by Wet Chemical Etching

InGaN/GaN multiple quantum wells （MQWs） are grown on planar and maskless periodically grooved sapphires by metal organic vapour phase epitaxy （MOCVD）. High-resolution x-ray rocking curves and transmission electron microscopy （TEM） are adopted to characterize the film quality. Compared with the MQWs grown on planar sapphire, the sample grown on grooved sapphire shows better crystalline quality： a remarkable reduction of dislocation densities is achieved. Meanwhile, the MQWs grown on grooved sapphire show two times larger PL intensity at room temperature. Temperature-dependent PL measurements are adopted to investigate the luminescence properties. The luminescence thermal quenching based on a fit to the Arrhenius plot of the normalized integrated PL intensity over the measured temperature range suggests that the nonradiative recombination centres （NRCs） are greatly reduced for the sample grown on grooved sapphire. We assume that the reduction of dislocations which act as NRCs is the main reason for the sample grown on pattern sapphire having higher PL intensity.     

使用SiNx原位淀积方法生长的GaN外延膜中的应力研究

采用低压MOCVD系统，在生长过程中使用SiN_x原位淀积的方法产生纳米掩模，并 在纳米掩模上进行选区生长和侧向外延制备了GaN外延薄膜.使用拉曼光谱和光荧光的手段对 GaN外延膜中的残余应力进行了研究.研究发现，用SiN_x原位淀积出纳米掩模后 ，GaN生长将由二维向三维转变，直到完全合并为止.利用拉曼光谱和光荧光谱分别研究了薄 膜中的残余应力，两者符合得很好；这种方法生长出的GaN薄膜的应力分布较传统的侧向外 延更加均匀；并且从中发现随着生长过程中SiN_x原位淀积时间的增加，生长在 其上的GaN外延膜中的残余应力减小.这是因为，随着SiN_x原位淀积时间的增加 ，SiN_x纳米掩模的覆盖度也增大.因此侧向外延区的比例增大，残余应力随之减 小. 关键词： GaN x原位淀积')" href="#">SiN_x原位淀积 拉曼 光荧光 残余应力