直接键合四结GaAs太阳电池研究

晶圆直接键合技术由于能将表面洁净的两个晶圆集成到一起，从而可以用来制备晶格失配 III-V族多结太阳电池。为了制备GaInP/GaAs/InGaAsP/InGaAs四结太阳电池，需采用具有低电阻率的GaAs/InP键合界面，从而实现GaInP/GaAs和InGaAsP/InGaA上下两个子电池的电学导通。我们设计并研究了具有不同掺杂元素和掺杂浓度的三种键合界面，并采用IV曲线对其电学性质进行表征。此外，对影响键合界面质量的关键工艺过程进行了研究，主要包括表面清洗技术和键合参数优化，例如键合温度、键合压力和键合时间等。最终制备出的键合四结GaInP/GaAs/InGaAsP/InGaAs太阳电池在AM0条件下效率最高达33.2%。

Direct-bonded four-junction GaAs solar cells

Direct wafer bonding technology is able to integrate two smooth wafers and thus can be used in fabricating III-V multijunction solar cells with lattice mismatch. In order to monolithically interconnect between the GaInP/GaAs and InGaAsP/InGaAs subcells, the bonded GaAs/InP heterojunction must be a highly conductive ohmic junction or a tunnel junction. Three types of bonding interfaces were designed by tuning the conduction type and doping elements of GaAs and InP. The electrical properties of p-GaAs (Zn doped)/n-InP (Si doped), p-GaAs (C doped)/n-InP (Si doped) and n-GaAs (Si doped)/n-InP (Si doped) bonded heterojunctions were analyzed from the I-V characteristics. The wafer bonding process was investigated by improving the quality of the sample surface and optimizing the bonding parameters such as bonding temperature, bonding pressure, bonding time and so on. Finally, GaInP/GaAs/InGaAsP/InGaAs 4-junction solar cells have been prepared by a direct wafer bonding technique with the high efficiency of 34.14% at the AM0 condition (1 Sun).