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题名	InGaN太阳能电池的制备及特性研究; Fabrication and Characteristics of InGaN Solar Cell
作者	雷廷平
答辩日期	2013 ; 2013
导师	张保平
关键词	InGaN Solar cell Homojunction (HOJ) Heterojunction (HEJ) High In content InGaN 太阳能电池 同质结（HOJ） 异质结（HEJ） 高In组分
英文摘要	Ⅲ族氮化物宽禁带材料的研究与应用是目前半导体行业的前沿和热点，主要包括GaN、InN、AlN及其三元和四元合金(InGaN，AlGaN，InAlN和AlInGaN)。其中InGaN材料以其优越的光伏特性，迅速成为近年来国际上的研究热点。它具有连续可调的宽带隙（0.65eV~3.42eV），其吸收光与太阳光谱几乎完美匹配，在整个组分范围内均为直接带隙材料，还具有高电子迁移率、高吸收系数、高硬度、强抗辐射能力等优点，在发展高效多节电池和空间太阳能电池上具有广阔的应用前景。本文围绕电池性能，在外延材料生长、结构设计、器件制作、性能表征等多方面进行了系统深入的研究，主要工作内容包括以下几个方面： （1）制作的低In组分InxGa1-xNp-i-n同质结（HOJ）太阳能电池具有良好的光电响应特性，x=0.02电池的开路电压（Voc）和填充因子（FF）分别高达2.24V和69%。进一步研究表明，随着In组分的提高，短路电流密度（Jsc）变大，而Voc却急剧减小，且下降幅度远大于材料带隙引起的减小量。通过多种表征手段深入分析了此现象的内在机理，提出高In组分样品中高密度缺陷是导致Voc降低的重要因素，提高材料质量是关键。 （2）结合外量子效率（EQE）响应谱，分析了p-GaN厚度对电池高能光子响应的重要影响，并阐明窗口层设计方面应侧重考虑的问题。 （3）研究光强和温度对电池性能的影响。随着光强增大，Jsc呈线性增大，Voc呈对数式增大，而FF及η因受串联电阻影响先增大后减小。温度升高电池性能总体变差，表现为Voc和η随温度升高而降低。 （4）基于HOJ电池的研究基础，改进结构制作异质结（HEJ）电池，并对比了具有相同耗尽区宽度的HOJ和HEJ电池，发现HEJ电池在制备高质量高In组分的InGaN吸收层，降低串联电阻，提高入射光的吸收，调制光谱响应等方面具有明显的优势，为InGaN太阳能电池的发展提供新思路。 （5）设计、制备三种不同电流扩展层（CSL）的In0.135Ga0.865N/GaN太阳能电池，并对比研究它们的性能。结果表明，CSL对电池性能影响很大，以ITO-L电池性能最佳。入射光的吸收和光生载流子的收集存在此消彼长的关系，合理设计找寻二者的平衡点以及提高p型掺杂均至关重要。 （6）制作InGaN/GaN多量子阱结构太阳能电池，其响应谱拓展到500nm以上，添加Al反射镜的电池转换效率达到0.335%。进一步研究不同垒厚对载流子输运的影响，结果表明减小垒厚可增大遂穿几率，提高光生载流子的收集，但也可能引起Voc变小。此外，还研发设计了垂直结构InGaN太阳能电池，并提出了多量子阱结构太阳能电池效率的改善途径。 （7）针对高效多节电池所需子电池的带隙，以及MOCVD生长中InN的高挥发性和NH3的低分解率问题，采用MBE外延高In组分InGaN薄膜。研究表明增大In的流量比r（r=In/(In+Ga)），可提高薄膜In的结合率，调整Ⅲ、Ⅴ族源流量，可避免In液滴形成并快速提高In的组分，甚至获得更高质量的外延膜，此外，较低的生长温度也有利于In结合，这些工作对将来高In组分电池的研究具有重要意义。; The group III nitride alloys and their application have become a hot research field in the semiconductor industry. Normally, they include GaN, InN, AlN and their ternary alloys (InGaN, AlGaN, InAlN) or quaternary alloys (AlInGaN). Recently, the InGaN alloy has attracted much attention due to its excellent photovoltaic properties. This alloy is of tunable direct bandgap (0.65 eV ~ 3.42 eV), with high carrier mobility, high absorption coefficient, high hardness, and superior radioresistance, and also showing the best match to the solar spectrum. The above properties promise to gain bright future of development of high-efficiency tandem cells and space solar cells (SCs). The present study concentrates on the solar cell performance and systematically investigates epitaxial growth, structural design, device fabrication, and performance characterization, etc. Main works are as follows: (1) The fabricated InxGa1-xN p-i-n homojunction (HOJ) SCs with low In content show excellent photoelectric response characteristics, e.g. when x = 0.02, an open circuit voltage (Voc) of 2.24 V and a fill factor (FF) of 69% are obtained. Further experiments on the cell performance depend on the In content reveal that with increasing In content, the short-circuit current density (Jsc) increases, but Voc decreases dramatically with a much larger value than the bandgap resulting reduction. Based on various characterization techniques, we investigated the possible mechanism and proposed that high density defect caused by high In content is the main reason for the dramatic Voc decrease, and the key is to improve the material quality. (2) Based on external quantum efficiency (EQE) spectra, we analyzed the effect of p-GaN layer thickness on the high-energy photon response and elucidated special references for the window layer design. (3) Law for the effect of light intensity and temperature on the cell performance. When light intensity is increased, Jsc increases linearly and Voc increases logarithmically; however, both FF and η first increase and then decrease due to the existing series resistance. On the other hand, with increasing temperature, the overall performance of the cells become worse, as suggested in Voc and η decrease. (4) Enlightened by HOJ SCs, we fabricate heterojunction (HEJ) SCs. Through comparison of HOJ and HEJ SCs, both having the same depletion width, we proposed that HEJ structure is a good alternative candidate for InGaN SCs. Because HEJ SCs show distinct advantages, such as growing high-quality InGaN absorption layer with high In content, reducing series resistance, improving the absorption of incident light, and modulating spectral response. (5) We have designed and fabricated In0.135Ga0.865N/GaN SCs with three different current spreading layers (CSLs). Results show that the cell with ITO layer type (ITO-L) presents the best performance. Also, there is a reciprocal relationship between the absorption of incident light and the collection of photo-induced carrier, suggesting that the importance of balance of the both and the p-type doping. (6) We also fabricate InGaN/GaN multiple quantum well SCs, whose response spectra expand above 500 nm. By adding Al-reflector, a conversion efficiency of 0.335% is obtained. Further study on barrier thickness and carrier transport suggests that thinning the barrier thickness increases the tunneling probability and improving the photo-induced carrier collection, but also result in the Voc reduction. Besides, we also develop the vertical structure InGaN SCs and put forward approaches for the efficiency improvement. (7) Aiming at the bandgap requirement for high efficiency tandem SCs, and high volatility in InN growth by MOCVD and the resulting low decomposition of NH3, we introduce MBE epitaxy to grow high In content InGaN films. Results show that increasing In flux ratio (r=In/(In+Ga)) and/or selecting low growth temperature can improve the combining rate of In, and by adjusting the ratio of group III and V sources, can avoid the In droplets formation such that improve the In content.; 学位：工学博士; 院系专业：物理与机电工程学院机电工程系_精密仪器及机械; 学号：19920090153652
语种	zh_CN
出处	http://210.34.4.13:8080/lunwen/detail.asp?serial=38091
内容类型	学位论文
源URL	[http://dspace.xmu.edu.cn/handle/2288/79129]
专题	物理技术－学位论文
推荐引用方式 GB/T 7714	雷廷平. InGaN太阳能电池的制备及特性研究, Fabrication and Characteristics of InGaN Solar Cell[D]. 2013, 2013.

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