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

The integration of transition metal dichalcogenides with photonic structures such as sol-gel SiO:TiO 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 MoS₂-based photodetector integrated with a sol-gel SiO:TiO 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 MoS₂ flake, which is deposited on the WG. Therefore, this device works as a photodetector. The light coupling into the MoS₂ 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 MoS₂-based photodetectors exhibit a photoresponsivity of 0.3 A W^-1 (n-type MoS₂) and 7.53 mA W^-1 (p-type MoS₂) 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.