局域表面等离激元增强AlGaN基紫外探测器的研究

发布时间：2017-12-31 19:25

本文关键词：局域表面等离激元增强AlGaN基紫外探测器的研究　出处：《华中科技大学》2016年博士论文　论文类型：学位论文

【摘要】：紫外探测技术在军用和民用领域均有着广泛应用,第三代宽禁带半导体材料AlGaN具有击穿场强高、热导率大、耐高温、抗辐照等特点,由其制备的紫外光电探测器特别适合用于军事、航天、工业等特殊环境。但是目前由于异质外延生长的AlGaN材料中缺陷密度偏高,同时受限于AlGaN材料的掺杂和器件工艺,AlGaN基紫外探测器的响应度仍然低于预期效果,特别是日盲紫外波段探测器的性能仍有较大提升空间。针对AlGaN基日盲紫外探测器研制中面临的关键问题,本文以经过优化MOCVD生长参数的AlGaN材料为基础,研究了高Al组份n型AlGaN欧姆接触制备,结合金属Al纳米颗粒的局域表面等离激元提升AlGaN基金属-半导体-金属型日盲紫外探测器的性能,并尝试将金属A1纳米结构与其他AlGaN基日盲紫外探测器集成。本论文的研究工作具体为以下几个方面：(1)探索高Al组分n型AlGaN材料的欧姆接触制备。我们提出并验证采用高温氮气退火可以修复高Al组分n型AlGaN材料中ICP刻蚀损伤,通过优化金属膜层、快速退火温度和时间等工艺参数,在ICP刻蚀并退火后的n型Al0.5Ga0.5N上制备了低阻欧姆接触,借助X射线光电子能谱测试阐明高温氮气退火的修复损伤机制。(2)利用纳米球刻蚀技术制备金属纳米结构,在不同基片上用旋涂法和漂移法实现大面积、低缺陷密度的单层PS球自组装模板,结合PS球模板形貌工艺,以此为金属蒸镀掩膜,可以制作多种金属纳米结构,包括不同尺寸的金属纳米颗粒阵列、金属纳米网等。(3)借助FDTD Solutions软件对纳米球刻蚀技术制备的三角柱状Al纳米颗粒建模,并研究了其局域表面等离激元共振与和颗粒尺寸、介质环境、入射光偏振性的关系,结合实验结果验证仿真模型,最终实现对Al纳米颗粒阵列的局域表面等离激元共振特性进行灵活调控。(4)将纳米球刻蚀技术制作的Al纳米颗粒阵列集成在AlGaN基MSM型日盲探测器表面,极大提高探测器的响应度并有效降低器件的暗电流,器件暗电流在pA量级,最高峰值响应度在20V偏压269nm处可达2.34A/W。研究了Al纳米颗粒尺寸、电极结构、工作偏压对于探测器性能的影响。我们初步探讨局域表面等离激元增强响应度机制。(5)提出具有纳米网状叉指电极的AlGaN基MSM型探测器的设计方案,对网状电极结构进行模拟优化并开展器件制备工艺研究。我们尝试性将A1纳米颗粒阵列与AlGaN基PIN型日盲紫外探测器集成,尚未实现增强响应度,需要进一步改进金属纳米结构设计。
[Abstract]:Ultraviolet detection technology has been widely used in military and civil fields. The third generation wide band gap semiconductor material AlGaN has the characteristics of high breakdown field, high thermal conductivity, high temperature resistance, radiation resistance and so on. The UV photodetectors prepared by them are especially suitable for military, aerospace, industrial and other special environments. But at present, the defect density of AlGaN materials grown by heteroepitaxial growth is on the high side. At the same time, the responsivity of AlGaN-based UV detectors is still lower than expected due to the doping of AlGaN materials and the fabrication of AlGaN-based UV detectors. Especially, the performance of solar blind UV detector still has great improvement space. The key problems in the development of AlGaN based solar blind ultraviolet detector are discussed. Based on the AlGaN material with optimized growth parameters of MOCVD, the ohmic contact preparation of n-type AlGaN with high Al content was studied in this paper. The properties of AlGaN based metal-semiconductor-metal solar blind UV detectors were improved by using local surface isoexcitators of Al nanoparticles. We also try to integrate metal A1 nanostructures with other AlGaN based diurnal blind UV detectors. The research work in this thesis is as follows: 1). The ohmic contact preparation of n-type AlGaN materials with high Al content was investigated. It was proposed and verified that high temperature nitrogen annealing can repair the ICP etching damage in n-type AlGaN materials with high Al content. Low resistivity ohmic contact was prepared on n-type ICP etched and annealed by optimizing the process parameters such as metal film, rapid annealing temperature and time. X-ray photoelectron spectroscopy (XPS) was used to explain the repair mechanism of high temperature nitrogen annealing. (2) Nanospheres etching technique was used to prepare metal nanostructures, and large area was realized by spin coating and drift method on different substrates. Low defect density single layer PS ball self-assembly template, combined with PS ball template morphology technology, can be used as metal evaporation mask to fabricate various metal nanostructures, including metal nanoparticles array of different sizes. FDTD Solutions software was used to model the triangular columnar Al nanoparticles prepared by nanospheres etching. The relationship between the local surface isoexciton resonance and particle size, dielectric environment and polarization of incident light is studied. The simulation model is verified by the experimental results. Finally, flexible regulation of the local surface isoexciton resonance characteristics of Al nanoparticles array is realized. The Al nanocrystalline array fabricated by nanospheres etching was integrated on the surface of AlGaN based MSM solar blind detector. The responsivity of the detector is greatly improved and the dark current of the device is reduced effectively. The dark current of the device is in the order of Pa. The maximum peak responsivity can reach 2.34 A / W at 269nm at 20V bias voltage. The size of Al nanoparticles and the electrode structure have been studied. The effect of operating bias on the performance of the detector. We discuss the mechanism of enhanced responsivity of local surface isopherons. The design scheme of AlGaN based MSM detector with nanometer mesh interDigital electrode is presented. The structure of the grid electrode was simulated and optimized, and the fabrication process of the device was studied. We tried to integrate the A1 nanoparticles array with the AlGaN based PIN solar blind UV detector, but the enhanced responsivity has not been achieved. The design of metal nanostructures needs to be further improved.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN23

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