Picosecond photoresponse in van der Waals heterostructures
Picosecond photoresponse in van der Waals heterostructures
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DOI：
10.1038/nnano.2015.227
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发表时间：
2016-01-01
影响因子：
38.3
通讯作者：
Koppens, F. H. L.
中科院分区：
文献类型：
--
作者：
Massicotte, M.;Schmidt, P.;Koppens, F. H. L.
石墨烯和过渡金属二硫属化物等二维晶体 (1) 表现出一系列独特且互补的光电特性 (2,3)。在垂直异质结构中组装不同的二维材料(4)可以将这些特性组合在一个器件中，从而创建具有卓越性能的多功能光电系统。在这里，我们证明石墨烯/WSe2/石墨烯异质结构将过渡金属二硫属化物(5,6)的高光电检测效率与与石墨烯(7-9)相当的皮秒光响应结合起来，从而优化了单个光电探测器的速度和效率。我们使用时间分辨光电流测量来跟踪这些器件中光激发载流子的提取，并证明光响应时间短至 5.5 ps，我们通过施加偏压和改变过渡金属二硫属化物层厚度来调整该时间。我们的研究提供了对控制这些范德华异质结构的检测速度和量子效率的物理过程的直接见解，例如面外载流子漂移和复合。对超快高效光电检测的观察和理解证明了混合过渡金属二硫属化物基异质结构作为未来光电器件平台的潜力。
Two-dimensional crystals such as graphene and transitionmetal dichalcogenides(1) demonstrate a range of unique and complementary optoelectronic properties(2,3). Assembling different two-dimensional materials in vertical heterostructures(4) enables the combination of these properties in one device, thus creating multifunctional optoelectronic systems with superior performance. Here, we demonstrate that graphene/WSe2/graphene heterostructures ally the high photodetection efficiency of transition-metal dichalcogenides(5,6) with a pico-second photoresponse comparable to that of graphene(7-9), thereby optimizing both speed and efficiency in a single photo-detector. We follow the extraction of photoexcited carriers in these devices using time-resolved photocurrent measurements and demonstrate a photoresponse time as short as 5.5 ps, which we tune by applying a bias and by varying the transition-metal dichalcogenide layer thickness. Our study provides direct insight into the physical processes governing the detection speed and quantum efficiency of these van der Waals heterostuctures, such as out-of-plane carrier drift and recombination. The observation and understanding of ultrafast and efficient photodetection demonstrate the potential of hybrid transition-metal dichalcogenide-based heterostructures as a platform for future optoelectronic devices.