二维MoS2/WSe2异质结的光电性能研究

近年来基于二维半导体过渡金属硫族化合物如MoS₂的光电晶体管被广泛研究。虽然基于单层MoS₂的光电探测器表现出较高的响应度,但是其较低的载流子迁移率也限制了响应时间,约在秒量级。二维半导体的相互堆垛可以形成具有低缺陷态且空间均匀的范德华异质结构,是提高二维光电探测器性能的有效途径。基于此本文通过机械剥离转移法构筑MoS₂/WSe₂垂直pn异质结,其较强的空间电荷区能有效地分离光生载流子,所以在自驱动状态下仍具有较好的光电探测能力,光响应度和探测率分别达到2.12×10³ A/W和2.33×10¹¹ Jones,同时极大地缩短了响应时间,响应时间达到40 ms。这种二维异质结器件制备方法简易,性能优异,在光电子领域具有广阔的应用前景。

Optoelectronic Properties of Two-Dimensional MoS2/WSe2 Heterojunction

In recent years, phototransistors based on two-dimensional semiconductors like transition metal di-chalcogenides including MoS₂ have been studied extensively. Although the phototransistor based on monolayer MoS₂ exhibits a high responsivity, its low carrier mobility also limits the response time of the photodetector to order of seconds. The stacking of two-dimensional semiconductors can form uniform van der Waals heterostructures with low trap defect states, and this is an effective way to improve the performance of two-dimensional photodetectors. In this work, MoS₂/WSe₂ vertical heterostructures were constructed via mechanical exfoliation and transferring method. The strong space charge region originating from the heterojunction can effectively separate the photo-generated carriers, therefore, the as-fabricated photodetectors have good photoelectric detection ability in self-powered mode. The responsivity and detectivity reach 2.12×10³ A/W and 2.33×10¹¹ Jones, respectively. Meanwhile, the response time of the heterojunction device greatly reduces to 40 ms. Such two dimensional heterojunction devices possess the advantages of simple fabrication method and good performance, and has a broad application prospect in the field of optoelectronics.