Thinning down the absorber layer of GaAs solar cells can reduce their cost and improve their radiation hardness, which is important for space applications. However, the lighttrapping schemes necessary to achieve high absorptance in these cells can be experimentally challenging or introduce various parasitic losses. In this work, a facile light‐trapping approach based on wet chemical etching is demonstrated. The rear‐side contact layer of ultrathin GaAs solar cells is wet‐chemically textured in between local Ohmic contact points using an NaOH‐based etchant. The resulting contact layer morphology is characterized using atomic force microscopy and scanning electron miscroscopy. High broadband diffuse reflectance and haze factors are measured on bare and Ag‐coated textured contact layers. The textured contact layer is successfully integrated as a diffusive rear mirror in thin‐film solar cells comprising a 300‐nm GaAs absorber and Ag rear contact. Consistent increases in short‐circuit current density (J_SC) of approximately 3 mA cm⁻² (15%) are achieved in the textured cells, while the open‐circuit voltages and fill factors do not suffer from the textured rear mirror. The best cell achieves a J_SC of 24.8 mA cm⁻² and a power conversion efficiency of 21.4%. The textured rear mirror enhances outcoupling of luminescence at open circuit, leading to a strong increase in the external luminescent efficiency.

中文翻译：

---

使用湿化学蚀刻的超薄砷化镓太阳能电池的简便捕光方法

减薄GaAs太阳能电池的吸收层可以降低其成本并提高其辐射硬度，这对于空间应用很重要。然而，在这些电池中实现高吸收率所必需的光捕获方案可能在实验上具有挑战性，或者会引入各种寄生损耗。在这项工作中，展示了一种基于湿化学刻蚀的简便光阱方法。使用NaOH蚀刻剂在局部Ohmic接触点之间对超薄GaAs太阳能电池的背面接触层进行了湿法化学织构化处理。使用原子力显微镜和扫描电子显微镜检查对所得的接触层形态进行表征。在裸露和涂有银的纹理接触层上测量到高宽带漫反射率和雾度因子。带纹理的接触层已成功地作为扩散后视镜集成到包含300 nm GaAs吸收剂和Ag后接触体的薄膜太阳能电池中。短路电流密度持续增加（在带纹理的电池中可达到约3 mA cm ^-2（15％）的J _SC，而开路电压和填充因数不受带纹理的后视镜的影响。最佳电池的J _SC为24.8 mA cm ^-2，功率转换效率为21.4％。带纹理的后视镜增强了开路时的发光输出耦合，从而大大提高了外部发光效率。