Department of Electrical Engineering and Computer Science , Vanderbilt University , Nashville , Tennessee 37235 , United States.
Department of Physics and Astronomy , Wayne State University , Detroit , Michigan 48201 , United States.
Nano Lett. 2018 May 9;18(5):2766-2771. doi: 10.1021/acs.nanolett.7b04205. Epub 2018 Apr 6.
We report high-performance WSe phototransistors with two-dimensional (2D) contacts formed between degenerately p-doped WSe and undoped WSe channel. A photoresponsivity of ∼600 mA/W with a high external quantum efficiency up to 100% and a fast response time (both rise and decay times) shorter than 8 μs have been achieved concurrently. More importantly, our WSe phototransistor exhibits a high specific detectivity (∼10 Jones) in vacuum, comparable or higher than commercial Si- and InGaAs-based photodetectors. Further studies have shown that the high photoresponsivity and short response time of our WSe phototransistor are mainly attributed to the lack of Schottky-barriers between degenerately p-doped WSe source/drain contacts and undoped WSe channel, which can reduce the RC time constant and carrier transit time of a photodetector. Our experimental results provide an accessible strategy to achieve high-performance WSe phototransistor architectures by improving their electrical transport and photocurrent generation simultaneously, opening up new avenues for engineering future 2D optoelectronic devices.
我们报告了具有二维（2D）接触的高性能 WSe 光电晶体管，该接触是在简并 p 型掺杂 WSe 和未掺杂 WSe 沟道之间形成的。同时实现了约 600 mA/W 的光响应率、高达 100%的高光外量子效率和短于 8 μs 的快速响应时间（上升和下降时间均较短）。更重要的是，我们的 WSe 光电晶体管在真空中表现出高的比探测率（约 10 琼斯），可与商业 Si 和 InGaAs 基光电探测器相媲美或更高。进一步的研究表明，我们的 WSe 光电晶体管的高光响应率和短响应时间主要归因于简并 p 型掺杂 WSe 源/漏接触和未掺杂 WSe 沟道之间不存在肖特基势垒，这可以减小光电探测器的 RC 时间常数和载流子输运时间。我们的实验结果提供了一种可行的策略，通过同时改善其电输运和光电流产生，来实现高性能 WSe 光电晶体管结构，为工程未来的二维光电设备开辟了新途径。
