Through a combined theoretical and experimental study, we have investigated the synthesis and performance characteristics of InGaN/Si double-junction photoelectrochemical (PEC) water splitting devices, which promise a theoretical solar-to-hydrogen conversion efficiency ∼30% under AM 1.5G one-sun illumination. The double-junction photocathodes consist of a p⁺-InGaN top light absorber and a Si bottom p-n junction, which are connected through a nanowire tunnel junction. The effect of indium composition of the top light absorber as well as the impact of p-type Mg dopant incorporation on the PEC performance was studied. Experimentally, the sample with 32% indium composition showed a maximum photocurrent density of ∼9 mA/cm² at 0.4 V vs reverse hydrogen electrode (RHE) with applied bias photon-to-current efficiency (ABPE) of ∼9.5%. An optimum p-type doping level ∼1 × 10¹⁷ cm⁻³ was also identified, which results in the best device performance as a result of optimum surface band bending as well as vertical charge carrier (hole) transport. These results also show a good agreement with our theoretical analysis. This work provides significant insights in advancing the design and development of high efficiency PEC devices for artificial photosynthesis using industry ready materials, e.g., Si and GaN, to achieve large-scale, low-cost onsite hydrogen fuel production.

中文翻译：

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InGaN/Si双结光电阴极的设计与性能

通过理论和实验相结合的研究，我们研究了 InGaN/Si 双结光电化学 (PEC) 水分解装置的合成和性能特征，该装置在 AM 1.5G 下有望实现约 30% 的理论太阳能到氢转换效率- 阳光照明。双结光电阴极由 ap ⁺ -InGaN 顶部光吸收体和 Si 底部 pn 结组成，它们通过纳米线隧道结连接。研究了顶部光吸收剂的铟成分的影响以及 p 型 Mg 掺杂剂掺入对 PEC 性能的影响。实验上，具有 32% 铟成分的样品显示最大光电流密度为 ~9 mA/cm ²在 0.4 V 与反向氢电极 (RHE) 相比，施加的偏置光子电流效率 (ABPE) 约为 9.5%。还确定了最佳 p 型掺杂水平 ~1 × 10 ¹⁷  cm ^-3，由于最佳表面带弯曲以及垂直电荷载流子（空穴）传输，这导致最佳器件性能。这些结果也与我们的理论分析非常吻合。这项工作为推进用于人工光合作用的高效 PEC 设备的设计和开发提供了重要见解，该设备使用工业就绪材料，例如 Si 和 GaN，以实现大规模、低成本的现场氢燃料生产。