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

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. The GaSe/MoS2 heterostructure exhibits a broadband photoresponse from visible to near‐infrared light. Moreover, the GaSe/MoS2 heterostructure with Ohmic‐contact ITO electrodes demonstrates a faster response than that with Schottky‐contact Ni/Au electrodes. Compared with Ohmic‐contact, the Schottky barrier between GaSe/MoS2 and Ni/Au electrodes restrain photocurrent and limit response time.