Choi Keorock, Kim Kyunghwan, Moon In Kyu, Bang Jangwon, Oh Jungwoo
School of Integrated Technology, Yonsei University, Incheon 21983, Republic of Korea.
Nanoscale. 2019 Aug 15;11(32):15367-15373. doi: 10.1039/c9nr03870a.
MacEtch allows subwavelength-structured (SWS) texturing on the GaAs surface without compromising crystallinity. The current density increases greatly, which is directly due to the reduction in the reflectance. Photons absorbed under reduced light reflectance are less affected by the charge recombination arising from crystal defects. The catalytic metal remaining after MacEtch serves as a catalyst for water splitting and increases the open-circuit potentials of the SWS GaAs photocathodes. The SWS GaAs not only amplifies the absorption of light, but also improves the collection of deeply generated photons at long wavelengths. The solar-weighted reflectance (SWR) of SWS GaAs is 6.6%, which was much lower than the 39.0% of bare GaAs. The light-limited photocurrent density (LLPC) increased by approximately 90% and the tafel slope improved as etching progressed. The external quantum efficiency was as high as 80%, especially at long wavelengths, after MacEtch. SWS GaAs photocathodes fabricated using MacEtch significantly reduce reflectance and recombination loss, thereby improving the key performance of PEC for hydrogen production. This technology can fully utilize the high absorption rate and carrier mobility of GaAs and is applicable to various photoelectric conversion device performance enhancements.
MacEtch 可在不影响结晶度的情况下，在砷化镓表面实现亚波长结构（SWS）纹理化。电流密度大幅增加，这直接归因于反射率的降低。在较低光反射率下吸收的光子受晶体缺陷引起的电荷复合影响较小。MacEtch 后残留的催化金属可作为水分解的催化剂，并增加 SWS 砷化镓光阴极的开路电位。SWS 砷化镓不仅增强了光吸收，还改善了长波长下深生光子的收集。SWS 砷化镓的太阳加权反射率（SWR）为 6.6%，远低于裸砷化镓的 39.0%。随着蚀刻的进行，光限制光电流密度（LLPC）增加了约 90%，塔菲尔斜率得到改善。MacEtch 后，外部量子效率高达 80%，尤其是在长波长下。使用 MacEtch 制造的 SWS 砷化镓光阴极显著降低了反射率和复合损失，从而提高了用于制氢的光电化学（PEC）的关键性能。该技术可充分利用砷化镓的高吸收率和载流子迁移率，适用于各种光电转换器件性能的提升。
