Enhanced photoresponse of a dielectric-free suspended WSe2–ReS2 heterostructure photodetector

Optoelectronic devices based on layered two-dimensional (2D) van der Waals (vdW) semiconductors and their heterostructures suffer from carrier scattering, trapping, and trap-assisted recombination-generation at the vdW channel/dielectric interface. In this work, we demonstrate improved photoresponse of a dielectric-free, suspended WSe2 (p)-ReS2 (n) heterostructure photodetector in comparison to an hBN dielectric-supported structure fabricated over a common local Au back gate. The dielectric-free suspension helps in eliminating optical losses at the 2D channel–dielectric interface and optical absorption loss in the dielectric itself as the metal (gold) gate aids in reflecting the incident light to enhance absorption in the 2D heterostructure. The increase in photocurrent increases with incident illumination power and is consistent over a wide range of wavelengths. Suspension of 2D layered materials, thus, paves the route for harnessing their intrinsic properties for next generation photodetection applications.