Modulating the detection performance of solution processed stacked multilayer-MoS 2 photodetectors upon ultraviolet–ozone surface treatment

In this study, we investigate the influence of ultraviolet–ozone (UV–O 3 ) treatment on the photodetection properties of multilayer-MoS 2 films. The MoS 2 thin film photodetectors were fabricated using a sequential spin coating process at low temperature. As UV–O 3 exposure time was increased, a significant enhancement in the photodetector performance at both ultraviolet and visible-light ranges has been observed. After 5 min of exposure to UV–O 3 , a 99% increase in the photoresponsivity to UV radiation, at wavelength of 320 nm, was observed under light intensity of 300 µW cm −2 . This remarkable improvement in UV detection was accompanied by a noteworthy enhancement through the whole visible range with a maximum responsivity of 128 A/W and a highest detectivity of 1.3 × 10 12 Jones at 580 nm irradiation. On the infrared side, a drop of 13.6% in responsivity and around an order of magnitude reduction in detectivity were noticed for 750 nm irradiation after the 5 min UV–O 3 treatment. All built detectors showed reliable photo-switching properties with response time of 0.22 s. Raman spectroscopy and X-ray photoelectron spectroscopy analysis suggest that the significant improvement of optoelectronic properties is caused by the passivation of localized Sulfur vacancies by O 2 or oxygen ions that bond chemically with MoS 2 . Such findings provide a quick and simple route for modulating the optical properties of MoS 2 -based optoelectronics through a surface treatment.