Van der Waals Heterostructure Photodetectors with Bias-Selectable Infrared Photoresponses.

A bias-selectable photodetector, which can sense the wavelength of interest by tuning the polarity of applied bias, is useful for target discrimination and identification applications. So far, those detectors are generally based on the back-to-back photodiode configuration via exploiting epitaxial semiconductors as optoelectronic materials, which inevitably lead to high fabrication costs and complex device architectures. Here, we demonstrate that our band-engineered van der Waals heterostructures can be applied as bias-selectable photodetectors. Our first prototypical device is mainly composed of black phosphorus (BP) and MoTe light absorbers sandwiching a thin MoS hole blocking layer. By varying the bias polarity, its spectral photoresponse can be switched between near-infrared and short-wave infrared bands, and our optoelectronic characterizations indicate that the detector can exhibit high external quantum efficiency (EQE) and fast operation speed. With this framework, we further demonstrate the detector with bias-selectable photoresponses within the mid-wave infrared band using BP/MoS/arsenic-doped BP heterostructures and show that our developed detectors can be integrated into a single-pixel imaging system to capture dual-band infrared imaging.