氮化镓（GaN）表面微纳米结构在界面改性和光电探测领域中的应用

发布时间：2018-01-04 21:03

  本文关键词：氮化镓（GaN）表面微纳米结构在界面改性和光电探测领域中的应用　出处：《山东大学》2017年博士论文　论文类型：学位论文

  更多相关文章： GaN极性 金属局域等离激元 Comsol有限元仿真 表面润湿性 光电响应

【摘要】：信息和能源技术的发展离不开半导体材料及高效率光电转换器件。以氮化镓(GaN)为代表的宽带隙半导体具有禁带宽度大,电子饱和漂移速度高、介电常数小、击穿场强大、导电导热性能好的特点,在国防、通讯、能源、照明、新能源汽车、智能电网等诸多领域均有极大的需求,是国际各国竞相发展的重要研究方向。基于以上研究背景,本论文深入研究GaN表面结构的制备方法,结合金属局域等离激元纳米结构,实现了 GaN表面润湿性能的调控;发现了 n型GaN的紫外光致亲水行为并证明其与GaN表面的杂质氧有关;结合有限元仿真分析方法,发现了 GaN的极化电场可以大幅度提高热电子的注入效率,从而有效提高了光电探测效率。本论文的正文部分共有五章,分别是第一章绪论;第二章GaN表面微纳米结构的制备及局域等离激元光学性质的仿真;第三章GaN表面微纳米结构对润湿性能的调控;第四章GaN表面微纳米结构对光电探测性能的调控;第五章结论与展望。主要研究内容和结论包括:第一章:细致阐述和分析了 GaN材料结构特征、物理性质及表面微纳米结构的制备方法,在此基础上,进一步详细综述了材料表面润湿性和半导体光电探测原理。第二章:1、研究了不同极性GaN表面腐蚀结构的制备方法及其反应机制。结论包括:(1)实现了 Ga极性GaN表面的无外加氧化剂腐蚀并研究了其腐蚀机制,发现在紫外光照下Au催化产生的羟基自由基可以实现GaN的氧化。(2)在N极性GaN表面利用KOH制备了金字塔状的腐蚀结构并研究了K2S208对腐蚀结构的影响。2、应用光化学法和溅射退火法实现了 Au、Ag纳米颗粒结构的制备并研究了其反应动力学特征。结论包括:(1)对于光化学法生长Au纳米颗粒,随着光照时间的延长,颗粒尺寸增大,密度增加。当光照时间为10min时,颗粒的平均粒径为～128.7nm,颗粒密度为～18.3/μ2。(2)在溅射退火法制备过程中,对于Au纳米颗粒,增加溅射时间和升高退火温度均可增加颗粒尺寸,降低颗粒密度。对于Ag纳米颗粒,增加溅射时间反而会减小颗粒尺寸,增加颗粒密度,而退火温度对纳米颗粒尺寸的影响不明显。3、利用Comsol Multiphysics有限元软件模拟仿真了金属纳米颗粒局域等离激元共振特征及其近场光学性质。结论包括:(1)Au纳米颗粒尺寸增大会导致光散射增强和局域等离激元共振峰红移。对处于空气中的Au纳米颗粒来说,当半径从5nm增加至50nm时,局域等离激元共振峰会有20nm的红移。颗粒越小,其周围电场强度越大。半径为5nm的Au颗粒其周围电场强度约是半径为50nm颗粒的103倍。(2)纳米颗粒周围介质折射率的增大会使光散射增强。对于GaN中半径为25nm的Au纳米颗粒,其局域等离激元共振处的光散射大于光吸收。而且,折射率大的介质会使等离激元共振峰产生明显红移,对半径为25nm处于GaN中的Au纳米颗粒,其共振峰要比在空气中时红移120nm。第三章:1、研究了 GaN的Ga面和N面微纳米结构对润湿行为的影响。结论包括:(1)Ga极性面和N极性面微纳米结构会使GaN更亲水,其中Ga极性面接触角最小可达21.8°,N极性面最小可达42.1°,月桂酸修饰后微纳米结构会使GaN更疏水,其中Ga极性面接触角最大可达138.5°,N极性面最大可达129.5°。(2)Ga极性和N极性GaN经月桂酸修饰后的微纳米结构表面可表现出高表面粘滞性。Ga极性GaN的前进和后退接触角之差最大可达40°,而N极性GaN可达 50°。2、研究了紫外辐照对GaN表面润湿性的影响。结论包括:(1)紫外辐照可导致n型GaN的接触角从原61.3°变至10°左右,且黑暗环境下放置可使接触角回复至初始状态。而上述过程对p型GaN则没有影响。(2)n型GaN具有紫外光致亲水性与表面杂质氧的减少有关,水分子在氧空位处进行解离吸附所形成的羟基基团使接触角大大降低;而p型GaN中由于氧含量低而不存在该过程。(3)n型GaN在表现出紫外光致亲水行为的同时,其光致发光谱中黄光带的发光强度大大增加,这是由于表面能带结构弯曲程度和耗尽层宽度的减小使辐射复合几率增大引起的,而p型GaN则没有该现象。第四章:1、研究了 CaN腐蚀结构对光电探测性能的调控。结论包括:GaN腐蚀后其光电流约是空白样品的1.65倍。在365nm处的光谱响应灵敏度约是空白样品的1.5倍,腐蚀后的样品响应时间比空白样品小。2、利用三明治结构的Au-Cu20验证了金属局域等离激元的光学性质对半导体光电探测性能的提高。结论包括:(1)电化学沉积过程中,Cu20的成核过程属于瞬时爆发成核。(2)Au纳米颗粒可以使Cu20光电探测器的光暗电流比提高199.7%(约是空白样品的3倍),光电转换效率提高54.3%。3、研究了 GaN的极性对金属纳米颗粒局域等离激元调控半导体光电探测性能的影响。结论包括:(1)金属纳米颗粒可以大大提高GaN的光电探测性能,其中Au纳米颗粒可以使GaN的光谱响应灵敏度在紫外和绿光部分分别是空白样品的54倍和64倍,而Ag纳米颗粒仅在紫外部分使GaN的光谱响应灵敏度提高,约是空白样品的18倍。(2)有限元仿真计算表明Au纳米颗粒增加的光吸收仅可使GaN的光谱响应灵敏度在紫外和绿光部分分别提高约4.4和3.1倍。该结果与N极性GaN上所测结果一致,但是却远远小于Ga极性GaN上测得的结果。(3)GaN极化场在促进热电子注入方面扮演了十分重要的角色。Ga极性GaN在紫外部分的高响应来源于极化场促进了热电子的注入;而在绿光部分的提高来源于局域等离激元共振时促进的缺陷电离。综上所述,我们在GaN上实现了腐蚀结构和金属纳米颗粒的制备,利用有限元仿真分析了金属纳米颗粒局域等离激元的光学性质,进而研究了上述两种表面微纳米结构对GaN表面润湿性能和光电探测性能的调控机制,最后结合有限元仿真结果和实验结果分析了 GaN极性在金属纳米颗粒局域等离激元调控GaN光电探测性能上的影响。本论文的创新之处在于(1)研究了 GaN光化学腐蚀特性,实现了 Ga极性GaN的无外加氧化剂腐蚀。研究了不同极性GaN表面的润湿行为并制备了疏水且具有高粘附性的GaN表面。(2)发现了 n型GaN的紫外光致亲水转变并证明其与GaN表面的杂质氧有关。(3)制备了等离激元半导体(Au-Cu2O)三明治结构并验证了利用局域等离激元提高半导体光电探测性能的可能性。(4)利用Au纳米颗粒局域等离激元效应实现了 GaN在紫外和绿光部分光谱响应灵敏度大幅度提升,证明了 GaN极化场有促进热电子注入的作用。
[Abstract]:The development of information technology and energy cannot do without semiconductor materials and high efficiency photoelectric converter. Using gallium nitride (GaN) as the representative of the wide band gap semiconductor with wide band gap, high electron saturation drift velocity, low dielectric constant, breakdown field strength, good thermal conductivity properties of the special point in national defense, communications, energy, lighting smart grid, new energy vehicles, and many other areas of great demand, is an important research direction in the international countries. Based on the above research background, this paper studies GaN surface structure preparation method, node metal localized plasmonic nanostructures with controlled GaN surface wettability was found; N type GaN ultraviolet light induced hydrophilic behavior and prove its related impurity oxygen GaN surface; combined with finite element analysis method, found the GaN polarization electric field can improve the efficiency of injected hot electrons substantially, from And effectively improve the photoelectric detection efficiency. Part of the body of this paper consists of five chapters. Chapter I is introduction; simulation of plasmonic optical properties of second GaN surface micro nano structure preparation and local regulation; the third chapter GaN surface micro nano structure on the wetting properties; the fourth chapter GaN surface micro regulation the nano structure of the photoelectric detection performance; the fifth chapter is conclusion and prospect. The main research contents and conclusions include: the first chapter: the detailed description and analysis of the structure characteristics of GaN material, preparation method of micro nano structure and physical properties of the surface, on this basis, further detailed review of the principle of surface wettability of material and semiconductor photoelectric detection. The second chapter: 1, study the different polar GaN surface corrosion structure preparation method and reaction mechanism. The conclusions include: (1) achieved without additional oxidant corrosion and its corrosion Ga polar GaN surface For that, the hydroxyl radical oxidation under UV Irradiation Catalyzed by Au can achieve GaN. (2) N in the polar GaN surface using KOH for corrosion structure Pyramid like prepared and studied the effect of K2S208 on corrosion structure of.2 by photochemical method and sputtering annealing method to achieve the Au, Ag nanoparticles the preparation and study of its reaction kinetics. The conclusions include: (1) for photochemical growth of Au nanoparticles, with the illumination time is prolonged, the increase of the particle size, the density increased. When the illumination time is 10min, the average size of the particles is ~ 128.7nm, 18.3/ ~ 2. mu of grain density (2) in the preparation of sputtering and annealing process for Au nanoparticles, increase the sputtering time and the annealing temperature can increase the particle size, particle density decreases. For Ag nanoparticles, increase the sputtering time but will reduce the particle size, the particle density increases, and back Effect of annealing temperature on the nano particle size was.3, the simulation of metal nanoparticles localized plasmon resonance characteristics and near-field optical properties by using Comsol finite element software Multiphysics. The conclusions include: (1) Au nano particle size increases will lead to light scattering enhancement and localized plasmon resonance peak of red shift. In the Au nano particles in the air, when the radius is increased from 5nm to 50nm, and other local 20nm plasmon resonance redshift summit. The smaller the particle is, the greater the field strength. Around the radius of Au 5nm particles around the field strength is about 103 times the radius of 50nm particles (2). Nano particles of the refractive index increases with light scattering enhancement. The GaN radius of Au nano particles 25nm, light scattering from the plasmon resonance of the localization is greater than the light absorption and refractive index of the medium will make the plasmon resonance peak. 鐢熸槑鏄剧孩绉，

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