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 x 10(4) at V-DS = +/- 1 V, and an excellent photoelectric performance, i.e., responsivity of approximate to 0.67 A W-1, specific detectivity of approximate to 2.3 x 10(11) cm Hz(1/2) W-1 and external quantum efficiency of approximate to 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 mu s, 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.