【作者】 杨利；

【导师】 薛成山；

【作者基本信息】 山东师范大学 ， 微电子学与固体电子学， 2003， 硕士

【摘要】 GaN是一种十分优异的宽带隙Ⅲ-Ⅴ族化合物半导体材料，是当前世界上最先进的半导体材料之一。室温下，GaN的禁带宽度为3.4eV，是制作光电子器件，尤其是蓝、绿发光二极管(LEDs)和激光二极管(LDs)的理想材料。这类光源在高密度光信息存储、高速激光打印、全色动态高亮度光显示、固体照明光源、高亮度信号探测、通讯等方面有着广阔的应用前景和巨大的市场潜力。此外，GaN也是制作高温、高频、大功率器件的理想材料。进入90年代之后，随着材料生长和器件工艺水平的不断发展和完善，一些突破性技术的实现使GaN材料的研究空前活跃，GaN已经成为世界各国争相研究的热点。目前，金属有机气相沉积(MOCVD)、分子束外延(MBE)和氢化物气相外延(HVPE)等方法已经成为制备GaN的主流工艺，其中MOCVD使用的最为广泛。采用上述方法制备GaN，工艺复杂，设备昂贵，限制了GaN材料的制备、生产和应用。现在，国际上有许多科研机构正在探索新的工艺方法，试图在合适的衬底上制备高质量的GaN薄膜。 具有纳米管和纳米线结构的纳米材料，因为在介观研究和制备纳米器件方面前景广阔，已成为当前研究的热点之一。近年来，由于一维GaN纳米结构在可见光和紫外光光电子器件方面的应用前景十分诱人，GaN纳米线的合成已经备受关注。从1999年开始，国际上掀起了合成一维GaN纳米结构的研究热潮。 本文采用简单、新颖的两步生长模式，在不同衬底上合成了高纯的一维GaN纳米结构和高质量的GaN晶体膜，详细地分析了合成产物的组分、结构和光致发光特性，初步提出并探讨了两步生长模式合成一维GaN纳米结构的 摘要生长机制，总结了影响一维GaN纳米结构和GaN 晶体膜生长的主要规律和因素。 1．创新性地开发出了氮化电泳或射频磁控溅射Ga。O。薄膜的两步生长工艺，成功地在石英、蓝宝石（A12O3）、St和 GaAs等不同衬底上合成了形态不一的高质量的一维GaN纳米结构。用两步生长模式合成的一维GaN纳米结构为高质量的六方单晶GaN，在室温下测得了良好的光致发光oL）特性。高分辨电镜（HRTEM）和能谱分析（EDX）说明合成的GaN纳米材料纯度非常高。两步生长模式克服了模板限制工艺、基于VLS机制的催化生长工艺和氧化辅助生长工艺无法避免引入杂质的缺点，有助于一维高纯GaN纳米结构光电特性的研究。 z．由两步生长模式合成的一维caw纳米结构的形貌受衬底的影响十分明显。我们可以通过选择不同的衬底来分别合成形态不同的一维GaN纳米结构，其中在石英衬底上合成的是平直的GaN纳米线，在蓝宝石衬底上合成的是细长透明的GaN纳米带，在GaAs衬底上合成的是柱状的一维GaN纳米结构，而在以衬底上合成的是粗短的GaN纳米棒。 3．氮化程序也会影响一维GaN纳米结构的形貌。我们通过改变氮化程序，分别在石英衬底上合成了平直的GaN纳米线和鱼骨形GaN纳米线。 4．选择合适的氮化温度才会得到理想的一维高纯GaN 纳米结构。氨化温度过低（低于900OC），氮化不完全，合成的一维GaN纳米结构的表层附着有Ga。O3颗粒。氮化温度过高（高于 1000 oC），一维 GaN 纳米结构的产量骤减，氮化温度升高到1050OC，一维GaN纳米结构基本消失。 5．在a衬底上生长高质量的GaN晶体膜也是本文研究的主要内容。扩Ga的出衬底可以降低 GaN与出衬底之间的晶格失·配，减小 GaN薄膜在衬底界面上产生的位错和缺陷，而且衬底表面的Ga有助于GaN在衬底表面结晶成核和 GaN薄膜的后序生长。我们采用两步生长模式成功地在扩Ga的引衬底上制备出了高质量的GaN晶体膜。GaN 晶体膜的生长过程与合成一维GaN纳米结构的程序相似。用该工艺生长的GaN晶体膜质量较高，位错和缺陷较少， ·2． 摘要呈六方单晶趋向，室温下获得了较好的光致发光特性。两步生长模式在扩Ga的出衬底上生长高质量的GaN晶体膜，有利于硅基光电集成的实现，向低成本主长高质量GaN晶体膜的研究方向迈进了一步。 6．实验发现，有氧化层p O的扩嫁St衬底不利于高质量GaN薄膜的生长。藏在有氧化层（SIO）的扩钦St衬底上，浓度分布不均匀，容易产生镜的合金点，在其上生长的GaN薄膜表面较粗糙。 7．Ga在衬底中的浓度分布也会对GaN薄膜的生长产生一定的影响。一般 Ga浓度高的引衬底有助于 GaN薄膜的生长，我们在扩 Ga浓度为 10‘、m”‘的引衬底（己去掉引。）上获得了高质量的GaN薄膜。更多还原

【Abstract】 Gallium nitride (GaN) is an excellent chemical semiconductor material and also is one of the most advanced semiconductors in the world. In fact, GaN has been regarded as one of the most promising materials for the fabrication of opto-electronic devices operating in the blue and near-ultraviolet (UV) regions, for instance light-emitting diodes (LEDs) and laser diodes (LDs), because it has large direct energy band gap of 3.4eV at room temperature. These light sources have promising applications and potential market demands for the high-density storage of opto-information, high-speed laser print, high-brightness and dynamic display in all colors, solid light sources, signal detectors and communication. In addition, GaN has been attracted much attention as a candidate for fabrication of high temperature, high frequency and high power devices. After 1990, the realization of some pivotally technical methods and the development of materials growth and devices technics made GaN to be the research focus of the world. MOCVD, MBE and HVPE have become dominating techniques to grow GaN materials. Among these methods, MOCVD is the most important and widely used by researchers. But now large-scale application of GaN devices is confined for the reason of costly equipments and complicated technics. Many research institutes and universities in the world are trying to grow GaN materials with simple and low cost methods.Nanometer-sized materials such as nanowires and nanotubes have gained considerable attention because of their potential applications in both mesoscopic research and the development of nanodevices. GaN at nano-dimensions, in particularly, as nanowires, is a good candidate for fabrication of nanometer sized opto-electronic devices. Since 1999, the synthesis of GaN structures has become one of the research focuses.In this paper, we have successfully synthesized high purity one-dimensionalGaN nano structures and high quality GaN crystal films with novel and simple two steps growth pattern. The composition, the structure and the photoluminescence properties of the fabricated products were analyzed in detail. The growth mechanism of two steps growth pattern were primarily discussed. We also summarized the rules and the effects to the growth of GaN nano structures and GaN films.1. One-dimensional GaN nano structures were synthesized on different substrates through nitriding 03263 films grown by radio frequency (r.f.) magnetron sputtering or electrophoresis. The synthesized GaN nano structures by the two steps growth pattern are hexagonal single crystal GaN. The photoluminescence (PL) properties of the formed one-dimensional GaN nano structures gained at room temperature revealed nicer results. The high resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray (EDX) suggested that the two steps growth pattern overcame the shortcomings of templet-confined reaction mechanism, catalytic reaction growth based on vapor-liquid-solid (VLS) mechanism and oxide-assisted growth mechanism, which would introduce contaminates unintentionally.2. The morphologies of one-dimensional GaN nano structures were affected greatly by substrates. We can get different one-dimensional GaN nano structures by choosing different substrates. Among the products, smooth and straight GaN nanowires on quartz substrates, long and transparent GaN nanobelts on sapphire substrates, short GaN nanorods on Si substrates and GaN nanopoles on GaAs substrates were found, respectively.3. The nitridation programs also affect the surface morphology of GaN nanowires. Different nitridation programs have produced straight and smooth GaN nanowires and herringbone GaN nanowires on quartz substrates, respectively.4. Choosing suitable nitridation temperature can get ideal one-dimensional GaN nano structures. Ga2O3 attached on the surface of one-dimensional GaN nano structures would be found if the nitridation temperature is low (<90更多还原