School of Electrical Engineering, Korea University , 136-701 Seoul, Republic of Korea.
Max-Planck-Institute for Solid State Research , Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
ACS Appl Mater Interfaces. 2017 Dec 13;9(49):42912-42918. doi: 10.1021/acsami.7b13395. Epub 2017 Dec 4.
Ultrathin sheets of two-dimensional (2D) materials like transition metal dichalcogenides have attracted strong attention as components of high-performance light-harvesting devices. Here, we report the implementation of Schottky junction-based photovoltaic devices through site-selective surface doping of few-layer WSe in lateral contact configuration. Specifically, whereas the drain region is covered by a strong molecular p-type dopant (NDP-9) to achieve an Ohmic contact, the source region is coated with an AlO layer, which causes local n-type doping and correspondingly an increase of the Schottky barrier at the contact. By scanning photocurrent microscopy using green laser light, it could be confirmed that photocurent generation is restricted to the region around the source contact. The local photoinduced charge separation is associated with a photoresponsivity of up to 20 mA W and an external quantum efficiency of up to 1.3%. The demonstrated device concept should be easily transferrable to other van der Waals 2D materials.
超薄二维（2D）材料片，如过渡金属二卤化物，作为高性能光收集器件的组成部分引起了强烈关注。在这里，我们通过在横向接触配置中对少层 WSe 进行选择性表面掺杂，实现了基于肖特基结的光伏器件。具体来说，漏极区域被强分子 p 型掺杂剂（NDP-9）覆盖以实现欧姆接触，而源极区域涂覆有 AlO 层，这导致局部 n 型掺杂，并相应增加接触处的肖特基势垒。通过使用绿光激光进行扫描光电流显微镜，可以确认光电流的产生仅限于源极接触周围的区域。局部光致电荷分离与高达 20 mA W 的光响应率和高达 1.3%的外量子效率相关。所展示的器件概念应该很容易转移到其他范德华 2D 材料。
