Photodetection Properties of MoS 2 , WS 2 and Mo x W 1-x S 2 Heterostructure: A Comparative Study.

Layered transition metals dichalcogenides such as MoS 2 and WS 2 have shown a tunable bandgap, making them highly desirable for optoelectronic applications. Here, we report on one-step chemical vapor deposited MoS 2 , WS 2 and Mo x W 1-x S 2 heterostructures incorporated into photoconductive devices to be examined and compared in view of their use as potential photodetectors. Vertically aligned MoS 2 nanosheets and horizontally stacked WS 2 layers, and their heterostructure form Mo x W 1-x S 2 , exhibit direct and indirect bandgap, respectively. To analyze these structures, various characterization methods were used to elucidate their properties including Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectrometry and high-resolution transmission electron microscopy. While all the investigated samples show a photoresponse in a broad wavelength range between 400 nm and 700 nm, the vertical MoS 2 nanosheets sample exhibits the highest performances at a low bias voltage of 5 V. Our findings demonstrate a responsivity and a specific detectivity of 47.4 mA W -1 and 1.4 × 10 11 Jones, respectively, achieved by Mo x W 1-x S 2 . This study offers insights into the use of a facile elaboration technique for tuning the performance of Mo x W 1-x S 2 heterostructure-based photodetectors.