Kang Ting, Jin Zijing, Han Xu, Liu Yong, You Jiawen, Wong Hoilun, Liu Hongwei, Pan Jie, Liu Zhenjing, Tang Tsz Wing, Zhang Kenan, Wang Jun, Yu Junting, Li Dong, Pan Anlian, Pan Ding, Wang Jiannong, Liu Yuan, Luo Zhengtang
Department of Chemical and Biological Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, William Mong Institute of Nano Science and Technology, and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China.
Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China.
Small. 2022 Jul;18(29):e2202229. doi: 10.1002/smll.202202229. Epub 2022 Jun 23.
Atomically thin monolayer semiconducting transition metal dichalcogenides (TMDs), exhibiting direct band gap and strong light-matter interaction, are promising for optoelectronic devices. However, an efficient band alignment engineering method is required to further broaden their practical applications as versatile optoelectronics. In this work, the band alignment of two vertically stacked monolayer TMDs using the chemical vapor deposition (CVD) method is effectively tuned by two strategies: 1) formulating the compositions of MoS Se alloys, and 2) varying the twist angles of the stacked heterobilayer structures. Photoluminescence (PL) results combined with density functional theory (DFT) calculation show that by changing the alloy composition, a continuously tunable band alignment and a transition of type II-type I-type II band alignment of TMD heterobilayer is achieved. Moreover, only at moderate (10°-50°) twist angles, a PL enhancement of 28%-110% caused by the type I alignment is observed, indicating that the twist angle is coupled with the global band structure of heterobilayer. A heterojunction device made with MoS Se /WS of 14° displays a significantly high photoresponsivity (55.9 A W ), large detectivity (1.07 × 10 Jones), and high external quantum efficiency (135%). These findings provide engineering tools for heterostructure design for their application in optoelectronic devices.
具有原子级厚度的单层半导体过渡金属二硫属化物（TMDs）具有直接带隙和强光与物质相互作用，在光电器件方面颇具潜力。然而，需要一种有效的能带对准工程方法来进一步拓宽其作为通用光电器件的实际应用。在这项工作中，通过两种策略有效地调整了使用化学气相沉积（CVD）方法制备的两个垂直堆叠的单层TMDs的能带对准：1）配制MoS Se合金的成分，以及2）改变堆叠异质双层结构的扭转角。光致发光（PL）结果与密度泛函理论（DFT）计算相结合表明，通过改变合金成分，可以实现TMD异质双层的连续可调能带对准以及II型-I型-II型能带对准的转变。此外，仅在中等（10°-50°）扭转角下，观察到由I型对准引起的PL增强28%-110%，这表明扭转角与异质双层的整体能带结构相互耦合。由14°的MoS Se /WS制成的异质结器件显示出显著高的光响应度（55.9 A W ）、大的探测率（1.07×10琼斯）和高的外量子效率（135%）。这些发现为异质结构设计提供了工程工具，以用于其在光电器件中的应用。
