Controlling the manner of band alignment of heterostructures increases design freedom with novel physical properties, enables the design of new functional devices, and improves device performance, but the lattice matching limits the diversity of traditional heterostructures. Van der Waals heterostructures (vdWHs) fabricated by rationally mechanical restacking different two-dimensional (2D) layered materials or sequential synthesis can overcome this limitation. However, it is difficult to achieve full control over the band alignment for a specific vdWHs by means of an applied vertical electric field. Here, we take advantage of the band structure alignment properties of narrow-bandgap black-arsenic (b-As) and large-bandgap WSe2 to realize b-As/WSe2 vdWHs with type-I band alignment. The band alignment can be tuned from type I to type II by gate electric field, which greatly improves the photoresponsivity over 103. An ultra-fast photoresponse of about 570 ns is obtained, which is much better than that of vdWHs with the same structure. The b-As/WSe2 vdWHs also can achieve high-performance rectifier phototransistor with an ultra-high rectification ratio exceeding 106, a small conductance slope of about 86 mV/dec, and a low curvature coefficient of about 46 V−1. Our work paves the way for the exploitation of b-As heterojunction for ultra-fast and low-power optoelectronic applications.

中文翻译：

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2D 黑砷/WSe2 异质结构中的门可控带对齐跃迁

控制异质结构的能带排列方式增加了具有新颖物理特性的设计自由度，使新功能器件的设计成为可能，并提高了器件性能，但晶格匹配限制了传统异质结构的多样性。通过合理地机械重新堆叠不同的二维 (2D) 层状材料或顺序合成制造的范德华异质结构 (vdWH) 可以克服这一限制。然而，很难通过施加的垂直电场实现对特定 vdWH 的带对齐的完全控制。在这里，我们利用窄带隙黑砷 (b-As) 和大带隙 WSe2 的能带结构排列特性来实现具有 I 型能带排列的 b-As/WSe2 vdWHs。带对准可以通过栅极电场从I型调谐到II型，这大大提高了103以上的光响应性。获得了约570 ns的超快光响应，这比具有相同结构的vdWHs要好得多。b-As/WSe2 vdWHs还可以获得超过106的超高整流比、约86 mV/dec的小电导斜率和约46 V-1的低曲率系数的高性能整流光电晶体管。我们的工作为开发用于超快和低功率光电应用的 b-As 异质结铺平了道路。b-As/WSe2 vdWHs还可以获得超过106的超高整流比、约86 mV/dec的小电导斜率和约46 V-1的低曲率系数的高性能整流光电晶体管。我们的工作为开发用于超快和低功率光电应用的 b-As 异质结铺平了道路。b-As/WSe2 vdWHs还可以获得超过106的超高整流比、约86 mV/dec的小电导斜率和约46 V-1的低曲率系数的高性能整流光电晶体管。我们的工作为开发用于超快和低功率光电应用的 b-As 异质结铺平了道路。