Highly Polarized and Fast Photoresponse of Black Phosphorus‐InSe Vertical p–n Heterojunctions

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AbstractThe van der Waals heterojunctions of 2D materials offer tremendous opportunities in designing and investigating multifunctional and high‐performance electronic and optoelectronic devices. In this study, a vertical p–n diode is constructed by vertically stacking p‐type few‐layer black phosphorus (BP) on n‐type few‐layer indium selenide (InSe). The photodetector based on the heterojunction displays a broadband and gate‐modulated photoresponse under illumination. More importantly, by taking advantage of the strong linear dichroism of BP, the device demonstrates a highly polarization‐sensitive photocurrent with an anisotropy ratio as high as 0.83. Additionally, the device can function in a zero‐bias photovoltaic mode, enabling a fast photoresponse and low dark current. The external quantum efficiency can reach ≈3%, which is impressive for BP‐based devices. The results pave the way for the implementation of p‐BP/n‐InSe heterostructure as a promising candidate for future multifunctional optoelectronics and, especially, polarization‐sensitive applications.