Ultra-broadband, self-powered and high performance vertical WSe2/AlOx/Ge heterojunction photodetector with MXene electrode

Two-dimensional materials/bulk semiconductor vertical van der Waals heterojunction are of great im-portance for high performance photodetector. However, their actualization are still impeded by their re-latively narrow response range and large amounts of interfacial defects. Herein, in light of the excellent optoelectronic properties of WSe2 and Ge, we design a kind of self-powered vertical WSe2/AlOx/Ge het-erojunction photodetector with MXene top electrode by simply stacking Ti3C2Tx MXene and WSe2 thin film on the AlOx/Ge substrate. The device enables an ultra-broadband spectral response from 405 nm to 3800 nm (mid-wave infrared light) because of the plasmon-induced hot electrons in the Ti3C2Tx MXene film. Also, the device proves the distinguished photodetection performance in terms of a large responsivity of similar to 1088 mA/W, a high specific detectivity of similar to 1.17 x 1012 Jones at 980 nm, and a fast response time of 43/ 63 mu s. The vertical stacking structure, the introduction of passivation layer and MXene electrode are con-sidered to be new strategies of designing heterojunction for ultra-broadband, low-power consumption and high performance next-generation photodetector.(c) 2022 Elsevier B.V. All rights reserved.