Research and Fabrication of UV SAM 4H-SiC APDs with Low Breakdown Voltage and Its p-type Ohmic Contacts

紫外微弱光信号和单光子信号的探测主要应用于激光诱导荧光性生物报警系统、非线性光线隐蔽通讯、非破坏性物质分析、高能物理、光时域反射和空气污染超高灵敏度探测等领域，它要求探测器具有高量子效率、低暗电流、低的过剩噪声和可见盲等特性，4H-SiC雪崩光电探测器（APD）是惟一能够满足这些要求的器件。 近年来，国际上已有研究小组对4H-SiCAPDs进行制备和研究，但所设计的APD结构较为简单，一般由PN结或者PIN结构成，不能有效地解决吸收层厚度对高量子效率、快响应速率和低击穿电压之间相互限制的矛盾；而已报道的分离吸收层与倍增层（SAM）结构4H-SiCAPDs的击穿电压过大；另外，对于金属与p型4...Low-level and single photon ultraviolet (UV) signal detections are mainly used in laser-induced fluorescence biological-agent detection, non-line-of-sight covert communica- tions, non-destructive material analysis, high energy physics, optical time domain reflectometer, ultra-high sensitivity for air contamination detection, and so on. 4H-SiC APD is the only promising UV detector that satisfies lo...学位：理学博士院系专业：物理与机电工程学院物理学系_凝聚态物理学号：B20042401

Reduce Ohmic Contact Resistance to p-GaN Using InGaN/AlGaN Superlattice

提出用P-IngAn/AlgAn超晶格作为P-gAn的接触层来获得低阻欧姆接触。通过一维薛定谔方程和泊松方程的自洽求解,得到了在极化效应影响下的IngAn/AlgAn,IngAn/gAn和gAn/AlgAn三种超晶格中Mg杂质离化率的空间分布。计算发现IngAn/AlgAn超晶格具有最高的Mg杂质离化率及最佳的空穴局域作用。最后,利用P-IngAn/AlgAn超晶格实验上实现了比接触电阻率为7.27x10-5Ω.CM2的良好欧姆接触。In order to achieve a smaller Ohmic contact resistance,p-InGaN/AlGaN superlattice was proposed to be used as the cap-layer of p-GaN.By making use the self consistent Poisson-Schrodinger calculations,obtained were the distributions of the ionization rate of Mg dopant in InGaN/AlGaN,InGaN/GaN and GaN/AlGaN superlattices when taking into account of the effect of polarization.It was found that the InGaN/AlGaN superlattice cap-layer had the largest ionization rate of Mg and the best confinement of the holes.Finally,the specific contact resistance of 7.27×10-5 Ω·cm2 was realized.国家自然科学基金项目(60276029);国家“863”计划项目(2004AA311020;2006AA032409);福建省科技项目(2006H0092;A0210006;2005HZ1018

Study of ICP-induced In doping and the properties of GaN-based LED wafers and devices

GaN材料属于第三代半导体材料，具有宽的直接带隙以及优异的物理和化学性质，是制作发光器件和光伏器件的理想材料。在信息显示领域，GaN基高亮度蓝、绿发光二极管可以用于户外大屏幕全色显示以及交通信号灯等方面；在照明领域，GaN基白光LED可以用于背光源、路灯和景观照明以及通用照明等。GaN基器件的研究已经取得巨大进展，但是在器件的制备过程中仍存在一些问题，如GaN材料的p型欧姆接触问题则是限制GaN器件发展的主要因素之一。有两方面的原因阻碍低阻p-GaN欧姆接触的实现：一方面是难以生长高空穴浓度的p-GaN材料；另一方面是缺乏合适的接触金属材料。目前用于提高p-GaN材料空穴浓度的方法主要有热退火...GaN-based wide-band gap semiconductors belong to the third generation of semiconductor materials, which are the ideal materials of emitting devices and photovoltaic devices because of their excellent physical and chemical properties. In the field of information display, GaN-based high-brightness blue and green light emitting diodes (LEDs) can be used in outdoor large screen display and traffic lig...学位：工学硕士院系专业：信息科学与技术学院_光学工程学号：2312012115289

Investigation of AlInGaN/GaN PIN Ultraviolet Photodiodes

摘要紫外光电探测器在航空、军事、民用等领域里具有非常重要的应用，本论文结合科研项目，进行了PIN结构紫外光电探测器的理论研究和实验制备。所做的研究工作如下：1、目前，GaN基紫外光电探测器一般采用AlGaN/GaN材料来制备，但是AlGaN与GaN之间晶格失配导致外延层位错密度较高，所以，我们提出用晶格常数和禁带宽度可以独立变化的AlInGaN四元合金代替AlGaN作为探测器的有源层。2、用MOCVD系统生长了与GaN晶格基本匹配的AlInGaN材料，通过X射线衍射分析该AlInGaN材料有较高的晶体质量。结合PL谱的测量，从理论上算出了该AlInGaN材料的组分为Al0.080In0.018...Abstract Ultraviolet photodiodes have the important applications in many fields, such as, navigate, military, some civil industries, this paper analyzes and makes a PIN photodiode both in theory and experiment. Main works include: 1. In recent year, GaN-based ultraviolet photodiodes are usually made with AlGaN/GaN materials, but the mismatch between AlGaN and GaN leads to the high ...学位：理学硕士院系专业：物理与机电工程学院物理学系_凝聚态物理学号：20022401

Development on AlInGaN/GaN PIN Ultraviolet Photodetectors

用AlInGaN四元合金代替AlGaN作为PIN探测器的有源层,研制出AlInGaNPIN紫外探测器。详细介绍了该器件的结构设计和制作工艺,并对器件进行了光电性能测试。测试结果表明,器件的正向开启电压约为1.5 V,反向击穿电压大于40 V;室温-5 V偏压下,暗电流为33 pA,350 nm处峰值响应度为0.163 A/W,量子效率为58%。Using AlInGaN instead of AlGaN as the source film of a photodetectors,an AlInGaN-based PIN UV photodetector was developed.Its device structure and fabrication processing are introduced in detail.Measurement results show that its turn-on voltage is about 1.5 V,and VBR>40 V;under-5 V bias voltage at room temperature,the dark current is about 33 pA;the peak responsivity can reach 0.163 A/ W at 350 nm,and the quantum efficiency is 58%.国家自然科学基金项目(60276029);; 国家“863”计划项目(2004AA311020,2006AA032409);; 福建省科技项目和基金项目(2006H0092,A0210006,2005HZ1018

Fabrication and Photovoltaic Properties of InGaN Solar Cells

III族氮化物（InN、GaN、AlN及其合金）由于其良好的光、电学特性已被广泛应用于制作短波长光电器件。近几年来，由于InGaN材料表现出来的优越的光伏特性，如禁带宽度大小可调（对应的光波长几乎覆盖整个太阳光谱）、电子迁移率高、吸收系数大、抗辐射能力强等，吸引人们探索其在高效率太阳能电池方面的应用。在本论文中，我们制作具有不同p-接触方案的InGaN同质结太阳能电池，并研究电池在不同In组分、照射光强度、环境温度下的光电响应特性。具体的研究内容如下： 1、制作具有Ni/Au半透明电流扩展层（SCSL）和叉指状（G）两种p型欧姆接触方案的In0.02Ga0.98Np-i-n同质结电池，并对比...III-nitride materials, represented by InN, GaN, AlN and their alloys, have been used to fabricate short-wavelength optoelectronic devices due to their favorable optical and electrical properties. Recently, the application has been extended to high-efficency solar cells due to their superior photovoltaic properties such as tunable energy band gaps of InGaN (which cover almost the whole solar spectr...学位：理学硕士院系专业：物理与机电工程学院物理学系_凝聚态物理学号：1982007115232

Research on GaN-Based solar cell and SnO-based thin film transistor devices

InGaN太阳能电池凭借其带宽可调且与太阳光谱完美匹配的特点，已成为国 际上氮化物材料和新型高效太阳能电池领域的研究热点。然而，随着In组分和 材料厚度的增加，InGaN材料出现相分离和产生大量缺陷，不仅降低了器件的内 量子效率，也对光生载流子的传输过程产生了重要影响。此外，目前普遍采用 的同侧电极结构也给电池的载流子输运、光入射以及尺寸增大带来了不利影响。 为突破传统InGaN太阳能电池的限制，本研究通过研制垂直结构InGaN太阳能 电池，采用垂直电极结构解决电流传输和电极吸光问题，利用电池表面粗化提 高器件外量子效率，通过增加底部反射镜使吸收区的厚度减小，进而缓解InGaN ...With the adjustable bandwidth and perfect match with solar spectrum, Indium Gallium Nitride (InGaN) solar cells, as one new type of semiconductor cells, have led the edge of the III-group nitrides and photovoltaic devices research field all over the world. However, with the increase of In composition and material thickness, InGaN-based material appeared phase separation and large amount of def...学位：工学博士院系专业：信息科学与技术学院_电路与系统学号：201419001

Monte-Carlo simulation of lifetime distribution on array interconnection of LED module

利用蒙特卡洛方法对阵列化互连lEd模组的可靠寿命进行了模拟,假设分档后的大功率白光lEd的正向电压符合正态分布,额定电流下的寿命符合对数正态分布,且寿命和电流、温度的关系符合EyIng模型,研究了nxn(6≤n≤12)lEd阵列的寿命分布。模拟结果表明,对于nxnlEd阵列,寿命随lEd数目的增加没有下降反而略有增加,表明对多数目lEd模组采用阵列化互连电路较传统串并联电路具有优势,能提高阵列的可靠性;对系统采用电流降额使用,可靠寿命随着电流降额量的增大而增大,电流降额越大,寿命增大越多;多数目lEd大阵列结合较高的电流降额量能大幅度提高系统的可靠性。Based on Monte-Carlo simulation,the lifetime distribution on array interconnection of high-power LED module is studied.It′s assumed that the forward voltage of power white LEDs follows normal distribution after bins,the mean lifetime at 350 mA follows Lognormal distribution,and the relationships between work current,temperature and lifetime are consistent with Eying model.For n×n LED array,the reliability lifetime does not decrease but increases slightly while the total number of LEDs increases.The results indicate that the array interconnect circuit has obvious advantage over the conventional series-parallel connection circuit,which can improve the reliability of LED array significantly.For different current derating values,the lifetime increases monotonically as the derating increases,and the larger the derating,the more increase of the lifetime.Especially,applying large derating to the array with a large number of LEDs can improve the reliability of LED array greatly.广东省自然科学基金资助项目(04011642);佛山市科技发展专项基金资助项目(04030021

Investigation of High Q Factor GaN-based Microcavity Light-Emitting Devices

GaN基微腔发光器件主要包括垂直腔面发射激光器（VCSELs）和谐振腔发光二极管（RCLEDs）。它们除了具有一般的半导体发光器件拥有的体积小、发光效率高、能耗低、方向性强等特点外，还具有圆形对称光斑，高纯度光谱等优点，此外，其方向性更强，发光效率更高，因而在固态照明，光存储，光通讯和显示等领域有着更为广阔的应用前景。品质因子（Q值）是衡量微腔发光器件性能的一个重要参数，Q值代表微谐振腔存储能量大小的能力，反应其总损耗的大小，Q值越大，意味着损耗越小。实现高Q值微腔发光器件是实现VCSELs和RCLEDs器件的重要基础。本论文针对GaN基微腔发光器件制作的难点问题展开研究，以获得高Q值的氮化物...GaN-based microcavity light-emitting devices such as vertical cavity surface-emitting lasers (VCSELs) and resonant cavity light-emitting diodes (RCLEDs) have attracted increasing attention due to their superior properties such as a narrower emission linewidth, circular beam shape, improved beam directionality and potential applications in solid-state lighting, optical storage, optical communicatio...学位：工学博士院系专业：物理与机电工程学院物理学系_微电子学与固体电子学学号：1982010015401