Tungsten-disulphide-based heterojunction photodetector.

Abstract

Two-dimensional (2D) materials have realized significant new applications in photonics, electronics, and optoelectronics. Among these materials is tungsten disulphide (WS2), which is a 2D material that shows excellent optoelectronic properties, tunable/sizable bandgap in the visible range, and good absorption. A polycrystalline WS2 thin film is successfully deposited on a substrate using radio frequency magnetron sputtering at room temperature. The x-ray diffraction pattern reveals two hexagonal structured peaks along the (100) and (110) planes. Energy-dispersive x-ray spectroscopy reveals a non-stoichiometric WS2 film with 1.25 ratio of S/W for a 156.3nm thick film, while Raman shifts are observed at the E2g1 and A1g phonon modes located at 350.70 cm-1 and 415.60 cm-1, respectively. A sandwiched heterojunction photodetector device is successfully fabricated and illuminated within the violet range at 441nm and 10V of bias voltage. The maximum photocurrent values are calculated as 0.95μA, while the responsivity is observed at 169.3 mA W-1 and detectivity 1.48×108 Jones at illuminated power of 0.6124μm. These results highlight the adaptability of the present technique for large-scale applications as well as the flexibility to promote development of advanced optoelectronic devices.