材料期刊网

Photoinduced second harmonic generation of Bi2S3 microcrystallite doped silica glass

Hongbing CHEN , Hai ping XIA , Congshan ZHU , Fuxi GAN

材料科学技术（英文）

Silica glasses doped with Bi2S3 microcystallite was prepared by the sol-gel process. Photoinduced second harmonic generation (SHG) was observed in the glass when it was irradiated with intense 1.06 μm and frequency doubled laser beams from a mode-locked Nd: YAG laser. It was found that the signal intensity increased with the irradiating time and approached a saturation gradually. The effect may be explained reasonably by the DC field model.

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Effect of Initialization Technical Parameters on Optical Absorption of Ge2Sb2Te5 Thin Films

Ming FANG , Qinghui LI , Fuxi GAN

材料科学技术（英文）

The optical absorption properties of phase-change optical recording thin films subjected to various initialization conditions were investigated. The effects of initialization power and velocity on optical constants of the Ge2Sb2Te5 thin films were also studied. The energy gap of Ge2Sb2Te5 thin films subjected to various initialization conditions was also obtained. It was found that the optical energy gap of the Ge2Sb2Te5 thin films increased with either increasing initialization laser power or decreasing initialization velocity, with peak of 0.908 eV at laser power of 1000 mW or initialization velocity of 4.0 m/s, but the continued increasing initialization laser power or decreasing initialization velocity resulted in the decrease of the optical energy gap. The change of the optical energy gap was discussed on the basis of amorphous crystalline transformation.

关键词: Phase transformation , null , null , null , null

TeOx Thin Films for Write-Once Optical Recording Media

Qinghui LI , Donghong GU , Fuxi GAN

材料科学技术（英文）

TeOx thin films were prepared by vacuum evaporation of TeO2 powder. Structural characteristic and surface morphology of the as-deposited films was analyzed by using X-ray photoelectron spectroscopy, transmission electron microscopy, X-ray diffractometer and atomic force microscopy. It was found that the films represented a two-component system comprising Te particles dispersed in an amorphous TeO¬2 matrix. The dispersed Te particles were in a crystalline state. The TeO¬x films showed a finely granular structure and a rough surface. Results of the static recording test showed that the TeO¬x films had good writing sensitivity for short-wavelength laser beam (514.5 nm). Primary results of the dynamic test at 514.5 nm were also reported. The TeO¬x films were suitable for using as a blue-green wavelength high density optical storage medium.

关键词: TeO¬ , null , null , null , null

GaN 纳米结构的制备

马洪磊 , 杨莺歌 , 薛成山 , 马瑾 , 肖洪地 , 刘建强

稀有金属 doi:10.3969/j.issn.0258-7076.2004.03.001

提出一种通过对溅射Ga2O3薄膜后氮化技术制备GaN纳米结构的方法,已成功地制备出 GaN 纳米线、纳米棒和纳米带.该方法既不需要催化剂,也不需要模板限制,不仅避免了杂质污染,而且简化了纳米结构的制造工艺,对于纳米结构的应用非常有利.利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和选区电子衍射(SAD)研究了 GaN 纳米结构的形貌和晶格结构.结果表明 GaN 纳米结构是具有六角纤锌矿结构的 GaN 晶体,不存在 Ga2O3 或 Ga 的其他相.研究结果证明在高温氮化过程中由于晶格缺陷的降低和晶化的改进能够得到高质量的 GaN 晶体.简要地讨论了GaN 纳米结构的生长机制.

关键词: GaN , 纳米结构 , 制备 , 后氮化技术

GaN基器件中的欧姆接触

邵庆辉 , 叶志镇 , 黄靖云

材料导报

GaN材料以其优良的光电性质,已成为制造发光器件和高温大功率器件的最有前途的材料.欧姆接触是制备GaN基器件的关键技术之一.着重论述了在n-GaN和p-GaN上制备欧姆接触的研究现状.

关键词: 氮化镓 , 欧姆接触 , 接触电阻率

Structure and Debye temperature of wurtzite GaN

Modern Physics Letters B

High Pure Wurtzite structure GaN has been synthesized by gas reaction method. Its structure was determined by powder X-ray diffraction using the Rietveld technique. The positions in the unit cell for Ga and N were refined to be (0, 0, 0) and (0, 0, 0.3814). The Debye temperature was determined as 586 K from the refined temperature factor by using the Debye approximation.

关键词: light-emitting-diodes;high-pressure phase;gallium nitride;transition;growth;blue

非极性GaN薄膜及其衬底材料

周健华 , 周圣明 , 邹军 , 黄涛华 , 徐军 , 谢自力 , 韩平 , 张荣

人工晶体学报 doi:10.3969/j.issn.1000-985X.2006.04.022

本文分析了在不同衬底上生长无极性GaN薄膜的情况,这些衬底主要包括γ-LiAlO2、r面蓝宝石等.通常在蓝宝石上制备的GaN外延膜是沿c轴生长的,而c轴是GaN的极性轴,导致GaN基器件有源层量子阱中出现很强的内建电场,发光效率会因此降低,发展非极性面外延,有望克服这一物理现象,使发光效率提高.

关键词: r面蓝宝石 , γ-LiAlO2 , a面GaN , m面GaN

GaN薄膜的研究进展

马洪磊 , 杨莺歌 , 刘晓梅 , 刘建强 , 马瑾

功能材料

由于GaN薄膜有希望应用在紫外或蓝光发光器件、探测器以及高速场效应晶体管、高温电子器件,GaN材料是当前研究的一个焦点.本文简要介绍了GaN薄膜的制备、衬底选择、掺杂、缓冲层、发光机制和表征等方面的最新进展,指出GaN材料进一步发展需要解决的关键技术问题.

关键词: GaN薄膜 , 研究进展 , 发光机制

低温GaN插入层对AlGaN/GaN二维电子气特性的改善

张东国 , 李忠辉 , 彭大青 , 董逊 , 李亮 , 倪金玉

人工晶体学报

利用低压MOCVD技术在蓝宝石衬底上生长了AlGaN/GaN二维电子气(2DEG)材料,在GaN生长中插入一层低温GaN,并研究了低温GaN插入层对二维电子气输运特性的影响.使用原子力显微镜(AFM)和非接触霍尔测试仪测量了材料的表面形貌和电学特性,发现低温GaN插入层可以改善材料表面平整度并使AlGaN/GaN 2DEG的电子迁移率有明显提高,GaN插入层温度为860℃的样品在室温下2DEG的电子迁移率达到2110 cm2/V·s.

关键词: MOCVD , 缓冲层 , AlGaN/GaN , 二维电子气

Effects of Mg Doping on Photoconductivity of GaN Films

Deheng ZHANG , Qingpu WANG , Yunyan LIU

材料科学技术（英文）

This paper presents the UV photoconductivity properties of GaN films doped with different Mg concentrations deposited by MOCVD. It was observed that for the undoped and weakly doped GaN films the UV photocurrent response was relatively large and the relax time was relatively short. With an increase in doped Mg content, the samples became p-type, the photocurrent response became weak and the relax time became longer.

关键词: GaN , null , null , null