The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, ON M5S 3G4, Canada.
Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, ON M5S 3E4, Canada.
Sci Adv. 2023 Apr 14;9(15):eadg2454. doi: 10.1126/sciadv.adg2454. Epub 2023 Apr 12.
Photocarriers predominantly recombine at semiconductor surfaces and interfaces, assuming high bulk carrier lifetime. Consequently, understanding the extraction of photocarriers via surfaces is critical to optoelectronics. Here, we propose Haynes-Shockley experiment analogs to investigate photocarrier surface extraction. A Schottky junction is used to tune the silicon near-surface electric field strength that varies over several orders of magnitude and simultaneously observe variations in broadband photocarrier extraction. Schottky barrier height and surface potential are both modulated. Work function tunable indium tin oxide (ITO) is developed to precisely regulate the barrier height and collect photocarriers at 0 V bias, thus avoiding the photocurrent gain effect. All experiments demonstrate >98% broadband internal quantum efficiency. The experiments are further extended to wave interference photonic crystals and random pyramids, paving a way to estimate the photogeneration rate of diverse surface light-trapping topologies by collecting nearly all photocarriers. The insights reported here provide a systematic experimental basis to investigate interfacial effects on photocarrier spatial generation and collection.
光生载流子主要在半导体表面和界面处复合，假设存在高体载流子寿命。因此，理解通过表面提取光生载流子对于光电至关重要。在这里，我们提出了 Haynes-Shockley 实验的模拟，以研究光生载流子的表面提取。肖特基结用于调节硅近表面的电场强度，该强度在几个数量级范围内变化，并同时观察宽带光生载流子提取的变化。肖特基势垒高度和表面电势都被调制。开发了功函数可调的铟锡氧化物（ITO），以精确调节势垒高度并在 0 V 偏压下收集光生载流子，从而避免了光电流增益效应。所有实验均证明宽带内量子效率 >98%。实验进一步扩展到波干涉光子晶体和随机金字塔，为通过收集几乎所有光生载流子来估计各种表面光捕获拓扑结构的光生速率铺平了道路。这里报道的见解提供了一个系统的实验基础，以研究界面效应对光生载流子空间产生和收集的影响。
