GaSe/MoS <sub/>2</sub> Heterostructure with Ohmica??Contact Electrodes for Fast, Broadband Photoresponse, and Selfa??Driven Photodetectors

摘要： In this letter, the vertically-stacked GaSe/MoS2 heterostructures with indium tin oxide (ITO) and Ni/Au as contact electrodes are successfully fabricated, respectively. The GaSe/MoS2 heterostructure exhibits a broadband photoresponse covering the range of visible to near-infrared spectra at room temperature without external bias voltage. When ITO serves as contact electrodes, a high rectification ratio, i.e., 1.5 × 104 at VDS = ±1 V, and an excellent photoelectric performance, i.e., responsivity of ≈0.67 A W-1, specific detectivity of ≈2.3 × 1011 cm Hz1/2 W-1 and external quantum efficiency of ≈160% at the wavelength of 520 nm is achieved. Moreover, the GaSe/MoS2 heterostructure with Ohmic-contact ITO electrodes demonstrates a faster response time of 155 μs, which is 4 times faster than the GaSe/MoS2 heterostructure with Ni/Au electrodes and about 300 times faster than previous reports. These results reveal the presence of an abrupt p–n junction between GaSe and MoS2 and significant role of electrode-contact mode in determining the photoelectric properties of GaSe/MoS2 heterostructure.