高效GaInP/GaAs/InGaAs/Ge多结太阳能电池生长和键合制备关键技术研究

According to Shockley-Quisser theory, multi-Junction GaInP/GaAs/InGaAs/Ge solar cell with bandgap energy of 1.9/1.4/1.0/0.67 eV is a best choice for full-spectrum absorption of solar energy, which could get the output of high voltage and low current, and reduce the resistive heat loss in the high power concentrator solar cells. In order to overcome the difficulties of high quality materials growth in this system, we explore a new method to get multi-junction solar cells by bonding based on the GaInP/GaAs/InGaAs grown by all solid-state molecular-beam-epitaxy (MBE) technique. The aim of this project is to explore the high quality material growth technology with components gradient technology and strain superlattices as the buffer layer on GaAs based GaInP/GaAs/InGaAs triple junction. By exploring the high-quality wafer bonding technology, the monolithic integration of three-junction cells with Ge will be achieved. In theory this multi-junction structure could access the conversion efficiency of more than 45%. The result of this investigation will certainly provide a viable solution to the development of multi-junction solar cells.

根据 Shockley-Quisser模型，带隙能量为1.9/1.4/1.0/0.67 eV的多结太阳电池可以满足对太阳光谱高效吸收，实现太阳能电池的高电压、低电流输出，同时该结构可以有效降低高倍聚光太阳电池中的电阻热损失，从而降低高倍聚光电池的使用成本。但目前通过生长直接得到满足此带隙组合的高质量多结太阳能电池仍存在很多问题。该项目针对其材料生长和器件制备的两个关键点，通过分渐变以及应变超晶格作为缓冲结构在GaAs衬底上实现高质量的GaInP/GaAs/InGaAs三结太阳能电池，并利用晶片键合技术工艺，探索解决关键制备问题，实现此三结电池与Ge电池的单片集成，得到带隙能量为1.9/1.4/1.0/0.67 eV的多结太阳电池，该电池在理论上可以获得超过 45%的转换效率。通过该项目实施所获得的技术突破将有助于推动高效太阳能电池的进一步发展。

本项目针对能源问题，希望通过器件研究，获得高电压，低电流输出，推动高倍聚光太阳电池中的进一步应用。主要通过晶片键合的工艺，在基于倒置结构生长的三结电池的基础上，制备GaInP/GaAs/In0.27Ga0.73As/Ge四结单片高效太阳电池。通过本项目的研究，掌握倒置结构的三结GaInP/GaAs/In0.27Ga0.73As结构中失配失配位错的控制，研究组分渐变以及应变超晶格不同缓冲结构对材料性能的影响，获得器件级的材料质量。利用晶片键合的方法，实现此三结电池与通过MOCVD设备生长扩散的Ge电池的四结单片集成，基于项目的研究目标，本项目在Ge基电池的MOCVD材料生长和光电性能表征、倒置三结太阳电池材料生长和器件制备以及基于键合的四结太阳电池制备三个方面开展了具体的研究，实现了项目立项时的研究目标，为下一步的工作奠定了良好的基础。