Integration of multi-layered materials with wide bandgap semiconductors for multi-spectral photodetectors: case for MoS2/GaN and β-In2Se3/GaN

We report on the demonstration of UV/visible and UV/near-IR photodetectors of high spectral responsivity (SR) in a non-conventional heterojunction, realized by combining multi-layered materials with wide band gap Gallium Nitride (GaN). Multi-layer MoS2 and beta-In2Se3 flakes were exfoliated separately on epitaxial GaN-on-sapphire, followed by fabrication of photodetectors in a lateral inter-digitated metal semiconductor metal geometry with Ti/Au contacts. Devices exhibited distinct steps in SR graph at 365 nm with responsivity value of 127 AW(-1) and at similar to 685 nm with responsivity value of 33 AW(-1) for MoS2/GaN heterostructure. Whereas, similar steps exhibited at 365 nm with responsivity value of 1.6 AW(-1) and at similar to 850 nm with responsivity value of 0.03 AW-1 in case of beta-In2Se3/GaN heterostructure. The wavelength dependent I-V characteristics showed photo-to-dark current ratio of similar to 30 at 685 nm in case of MoS2/GaN heterostructure and ratio of similar to 2 at 850 nm for beta-In2Se3/GaN heterostructure. The reasons which limit the performance of the devices were also investigated using transient analysis and power dependent responsivity analysis. In summary, current work paves the way for futuristic layered-materials/3D heterostructure devices.