High performance ambipolar response photodetectors based on ReS2/PdSe2 van der Waals heterostructures

Anomalous negative photoresponse in a photodetector where the current is reduced under light illumination holds great potential in the application of next-generation novel and multifunctional optoelectronic devices. Until now, the figure of merits for negative photodetectors, such as responsivity and response speed, still exhibit unsatisfactory performance when compared to their positive counterparts. In this work, an unique gate voltagedependent ambipolar-response photodetector based on the ReS2/PdSe2 heterostructure with excellent characteristics are prepared and investigated systematically. The evolution for concentration of hole in PdSe2 by gate voltage and the trap states existed at the surface and interface play a dominant role in the transition of negative to positive response. The negative photoresponse performances in terms of responsivity, external quantum efficiency (EQE), and response speed under 638 nm light illumination, are as high as about 532 A/W, 105%, and as fast as 7.9/8.7 mu s, respectively. Meanwhile, the corresponding values of the positive response also reach to 10.5 A/W, 2069%, and 30 mu s, respectively, demonstrating the superiority of this heterostructure at ambipolar response. In addition, a similar phenomenon is also observed at the near-infrared region (980 nm). The discovery of these results signifies a pronounced breakthrough in the field of ambipolar photodetectors, thereby paving the way for future advancements in optoelectronic applications.