Vertical MoSe₂-MoO _x p-n heterojunction and its application in optoelectronics

The hybrid n-type 2D transition-metal dichalcogenide (TMD)/p-type oxide van der Waals (vdW) heterojunction nanosheets consist of 2D layered MoSe₂ (the n-type 2D material) and MoO _x (the p-type oxide) which are grown on SiO₂/Si substrates for the first time via chemical vapor deposition technique, displaying the regular hexagon structures with the average length dimension of sides of ∼8 μm. Vertical MoSe₂-MoO _x p-n heterojunctions demonstrate obviously current-rectifying characteristic, and it can be tuned via gate voltage. What is more, the photodetector based on vertical MoSe₂-MoO _x heterojunctions displays optimal photoresponse behavior, generating the responsivity, detectivity, and external quantum efficiency to 3.4 A W^-1, 0.85 × 10⁸ Jones, and 1665.6%, respectively, at V _ds = 5 V with the light wavelength of 254 nm under 0.29 mW cm^-2. These results furnish a building block on investigating the flexible and transparent properties of vdW and further optimizing the structure of the devices for better optoelectronic and electronic performance.