An In0.42Ga0.58N tunnel junction nanowire photocathode monolithically integrated on a nonplanar Si wafer
An In0.42Ga0.58N tunnel junction nanowire photocathode monolithically integrated on a nonplanar Si wafer
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DOI：
10.1016/j.nanoen.2018.12.067
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发表时间：
2019-03
期刊：
影响因子：
17.6
通讯作者：
Yongjie Wang;S. Vanka;J. Gim;Yuanpeng Wu;Ronglei Fan;Yazhou Zhang;Jinwen Shi;M. Shen;R. Hovden;Z. Mi
中科院分区：
文献类型：
--
作者：
Yongjie Wang;S. Vanka;J. Gim;Yuanpeng Wu;Ronglei Fan;Yazhou Zhang;Jinwen Shi;M. Shen;R. Hovden;Z. Mi
III族氮化物半导体表现出许多理想的太阳能水分解特性，包括几乎整个太阳光谱的可调能带隙和在可见光和近红外光照射下用于水氧化和质子还原的合适带边位置。然而，迄今为止，III族氮化物半导体光电阴极的最佳能量转换效率仍低于1%。在这里，我们报告了一个相对高效的p型In 0.42Ga 0.58N光电阴极，这是单片集成在ann型非平面硅晶片通过GaN纳米线隧道结的演示。开放柱设计，连同非平面Si晶片可以显着最大化光捕获，而隧道结降低了界面电阻，并提高了光生电子的提取。此外，在InGaN纳米线表面光沉积Pt纳米颗粒显着提高阴极性能。该纳米线光电阴极在AM 1.5 G单太阳照明下，0 V vs. RHE时的光电流密度为12.3 mA cm− 2，起始电位为0.79 V vs. RHE。最大施加偏压的光电流效率达到4%，在~0.52 V与RHE，这是一个数量级高于先前报道的III族氮化物光电阴极的值。值得注意的是，在不使用任何额外表面保护的情况下，在稳定的光电流密度约为12 mA cm− 2的情况下，超过30小时的太阳能水分解没有测量到性能下降，这归因于InGaN纳米线的N端表面的自发形成以防止光腐蚀。
Group III-nitride semiconductors exhibit many ideal characteristics for solar water splitting, including a tunable energy bandgap across nearly the entire solar spectrum and suitable band edge positions for water oxidation and proton reduction under visible and near-infrared light irradiation. To date, however, the best reported energy conversion efficiency for III-nitride semiconductor photocathodes is still below 1%. Here we report on the demonstration of a relatively efficientp-type In0.42Ga0.58N photocathode, which is monolithically integrated on ann-type nonplanar Si wafer through a GaN nanowire tunnel junction. The open pillar design, together with the nonplanar Si wafer can significantly maximize light trapping, whereas the tunnel junction reduces the interfacial resistance and enhances the extraction of photo-generated electrons. In addition, photodeposited Pt nanoparticles on InGaN nanowire surfaces significantly improve the cathodic performance. The nanowire photocathode exhibits a photocurrent density of 12.3 mA cm−2at 0 V vs. RHE and an onset potential of 0.79 V vs. RHE under AM 1.5 G one-sun illumination. The maximum applied bias photon-to-current efficiency reaches 4% at ~0.52 V vs. RHE, which is one order of magnitude higher than the previously reported values for III-nitride photocathodes. Significantly, no performance degradation was measured for over 30 h solar water splitting with a steady photocurrent density ~12 mA cm−2without using any extra surface protection, which is attributed to the spontaneous formation of N-terminated surfaces of InGaN nanowires to protect against photocorrosion.