【作者】 罗述东；

【导师】 周维亚；

【作者基本信息】 中国科学院研究生院（物理研究所） ， 凝聚态物理， 2006， 博士

【摘要】 在Ⅲ族氮化物半导体中,InN具有优异的电子输运性质,在高频厘米和毫米波器件应用上具有独特的优势,这些特性引起人们对InN的极大兴趣。同时,近两年来的研究表明InN的带隙宽度大约在0.7eV,远低于早期的研究结果（1.9eV左右）,目前这仍是人们争议的焦点之一。由于纳米半导体材料与相应的体材料相比,在光学性质、电学性质和光电转换方面都有显著的不同,因此,开展一维InN纳米结构的工作对理论研究和潜在的器件应用都具有重要意义。本论文“氮化铟一维纳/微米结构的可控制备和表征”主要包括以下几方面工作:第一,采用化学气相沉积工艺,分别以In₂O₃为In源、NH₃为N源原位合成直径均匀、结晶性很好、生长方向统一的纤锌矿结构InN纳米线,在此基础上通过调节生长参数,进而制备出纳米带和微米管结构。纳米结构产量高,从反应物到产物的转化率高,成份纯净。微米管为六边形截面的螺旋型结构,同时具有左手、右手螺旋,螺旋角分布宽。在系列实验和详细的形貌观察的基础上,对纳米线、纳米带和微米管的生长机理进行分析,发现InN基于自身演变从一种结构向另一结构变化的独特现象;第二,采用Raman、光致发光、光吸收、PPMS、热重等分析手段研究了InN纳米/微米结构的光学、电学、热学等性质。观察到四个InN Raman散射的特征模以及它们的温度依赖现象。观察到InN纳米结构精细发光谱,并初步探讨了各荧光峰的起因。光吸收研究发现中心在0.2eV附近的吸收峰和Tauc光吸收边因产物的生长时间延长而规律性移动,该现象还与产物成分、几何结构相关。由于InN纳米线中高的自由载流子浓度,而导致材料表现出金属导电行为。TG与DSC分析表明InN纳米结构的起始分解温度和氧化温度分别为576和390℃;第三,在低真空条件下对各种InN结构进行了热氧化处理,对InN纳米结构的氧化过程进行了研究,并获得In₂O₃/InN复合纳米结构。通过控制氧化处理,实现了六方纤锌矿型InN纳米/微米结构向体心立方结构In₂O₃的直接转化,并维持了反应物的原始几何形貌,且反应温度较低。为In₂O₃纳米/微米结构的合成提供了一条新途径。更多还原

【Abstract】 Particular interests have been arisen in InN semiconductor, owing to its superior electronic transport characteristics to other Ill-nitride semiconductors that suggests there may be distinct advantages offered by using InN in high frequency centimeter and millimeter wave devices. In addition, studies in the last few years demonstrated a band-gap energy around 0.7 eV for InN, which is much smaller than the previous reports （-1.9 eV）. Thus, the band-gap energy of InN is still under debate. Furthermore, nanostructured materials are appealing and fascinating in optical, electrical and optoelectronic conversion properties, different from their bulk counterparts. Therefore, the study of one-dimensional InN nanostructures is of benefit to fundamental theoretic research and to potential device applications.The dissertation "Controllable Preparation and Characterization of One-Dimensional Nano/Microstructures of Indium Nitride" essentially involves following investigations:Firstly, wurtzite InN nanowires with uniform diameters, good crystallinity and homogeneous growth direction were synthesized by using In₂O₃ powers and NH3 as indium and nitrogen sources respectively via a conventional chemical vapor deposition process. Adjustments of reaction parameters led to the growth of nanobelts and microtubes. The as-prepared nanostructured products manifested high purity, high yield and high conversion ratio from In₂O₃ to InN. The InN microtubes are hexagonal in cross section and exhibit helical structure with both right-handed and left-handed helicities and a wide distribution of helical angles. Based on series of comparative experiments and detailed morphology imaging, the growth mechanisms of InN nanowires, nanobelts and microtubes were discussed and a unique phenomenon was revealed that InN changes from one nanostructure to another via self-evolution.Secondly, we have studied the optical, electrical and thermodynamic properties of InN nano/microstructures by using Raman, photoluminescence, optical absorption, PPMS and thermogravimetry measurements. Four characteristic modes of InN Raman scattering were observed and their temperature dependences were investigated. Fine structures in the luminescence spectra of InN nanostrutures were obtained and the emission band relating to the structures were discussed tentatively. In the optical absorption spectra, both the peak centered at about 0.2 eV and Tauc absorption edge shift systematically as the function of reaction time of the products, which is related to the composition and geometrical shape of the as-prepared products. Due to the high carrier concentration, a single InN nanowire exhibits electrical transport property characteristic of metals. TG and DSC analyses revealed that InN nanostructures began to decompose at 576°C and to be oxidized at 390°C, respectively.Thirdly, thermal oxidation of InN nano/microstructures has been performed under a low vacuum. The oxidation process of InN nanowires was investigated and InO₃/InN composite nanostructure was obtained. By the controlled oxidation treatment, InN nano/microstructures in wurtzite were converted directly into bcc In₂O₃ counterparts preserving the original geometrical shape of InN nano/microstructures, which demonstrates a novel approach to the preparation of In₂O₃ nano/microstructures with peculiar geometry.更多还原