GaSe/MoS2 Heterostructure with Ohmic‐Contact Electrodes for Fast, Broadband Photoresponse, and Self‐Driven Photodetectors

Abstract In this letter, the vertically‐stacked GaSe/MoS 2 heterostructures with indium tin oxide (ITO) and Ni/Au as contact electrodes are successfully fabricated, respectively. The GaSe/MoS 2 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 × 10 4 at V DS = ±1 V, and an excellent photoelectric performance, i.e., responsivity of ≈0.67 A W ‐1 , specific detectivity of ≈2.3 × 10 11 cm Hz 1/2 W ‐1 and external quantum efficiency of ≈160% at the wavelength of 520 nm is achieved. Moreover, the GaSe/MoS 2 heterostructure with Ohmic‐contact ITO electrodes demonstrates a faster response time of 155 µs, which is 4 times faster than the GaSe/MoS 2 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 MoS 2 and significant role of electrode‐contact mode in determining the photoelectric properties of GaSe/MoS 2 heterostructure.