Waveguide-Coupled Light Photodetector Based on Two-Dimensional Molybdenum Disulfide.

The integration of transition metal dichalcogenides with photonic structures such as sol-gel SiO x :TiO y optical waveguides (WGs) makes possible the fabrication of photonic devices with the desired characteristics in the visible spectral range. In this study, we propose and experimentally demonstrate a MoS 2 -based photodetector integrated with a sol-gel SiO x :TiO y WG. Based on the spectroscopic measurements performed for our device, we concluded that the light entering the WG is almost completely channeled out from the WG and absorbed by the MoS 2 flake, which is deposited on the WG. Therefore, this device works as a photodetector. The light coupling into the MoS 2 region in this device construction is due to the high contrast of refractive index between the van der Waals crystal and the sol-gel WG, which is ∼4 and ∼1.8, respectively. The obtained MoS 2 -based photodetectors exhibit a photoresponsivity of 0.3 A W -1 ( n -type MoS 2 ) and 7.53 mA W -1 ( p -type MoS 2 ) at a bias voltage of 2 V. These results reveal great potential in the integration of sol-gel WGs with van der Waals crystals in optoelectronic applications.