Sm, Pt asymmetric n- and p-type contacts in WSe2 phototransistor for high-performance broadband photodetection

The development of high-performance broadband photodetectors working at room temperature is still attractive. The Schottky barrier phototransistor based on asymmetric junction seems to be endowed with such potential—as photodetectors with low device power consumption and high photoresponse; however, it is rarely studied. Herein, a Sm–WSe2–Pt phototransistor with asymmetric metal contacts is constructed, and it is systematically investigated for their electronic and photoelectronic tunability via gate voltage, wavelength, and illumination power density. It was found that the tunable photogating process dominates the photoresponse mechanism, which allows for an excellent broadband photodetection from 300 to 1000 nm wavelength. In addition, the responsivity (R) and specific detectivity (D*) at 450 nm can reach 1723 A/W and 2.3 × 1013 Jones, respectively, while that of infrared illumination of 900 nm can reach 4.7 A/W and 3.1 × 1010 Jones, respectively. In addition, the device exhibits obvious photoresponse at zero bias, the R and D* can reach up to 27 mA/W and 8.5 × 1010 Jones, which realizes self-driven photodetection. This work provides an optimal option for realizing high-integrated, high-performance, low-power-consuming, and room-temperature-working broadband photodetectors.