Asymmetric Contacts on Narrow-Bandgap Black Phosphorus for Self-Driven Broadband Photodetectors

Self-driven broadband photodetectors based on two-dimensional (2D) materials have attracted considerable interest for their outstanding optoelectronic properties. Asymmetric contact induced potential barrier on 2D narrow-bandgap materials is a feasible scheme for self-driven broadband photodetectors, but has not been constructed untill now due to the band structure mismatch of the channel and metal electrodes. Herein, a self-driven broadband photodetector is reported covering from visible to infrared spectrum by well designing the band structure of the Cr/BP/WTe2 heterostructure with asymmetric contact architecture, constructing a huge potential barrier at the two ends of the black phosphorus (BP) channel due to the perfect ohmic and Schottky contacts at the WTe2-BP and Cr-BP interfaces, respectively. The as-fabricated device exhibits responsivity of & SIM;283 and & SIM;193 mA/W under 532 and 1550 nm illumination, respectively, under zero bias with corresponding detectivity of & SIM;2.3x1011 and & SIM;1.2x1011 Jones. The results demonstrate that the well-designed band structure can be adopted to construct ideal Schottky and ohmic contact on 2D narrow-bandgap materials to realize a self-driven broadband photodetector. These findings highlight a simple and novel strategy for constructing predesigned band structure for further electronic and optoelectronic applications. Asymmetric Schottky and ohmic contacts at the two ends of black phosphorus nanosheets have been fabricated by using Cr and WTe2 electrodes to construct a huge potential barrier for a self-driven broadband photodetector with a high detectivity of & SIM;2.3x1011 Jones under zero bias, highlighting a simple and novel strategy for constructing predesigned band structure for further electronic and optoelectronic applications.image