Correlating Carrier Localization to Optoelectronic Behavior of Monolayer MoS₂

In nanoscale semiconductor devices, electrical conductivity is significantly influenced by inherent disorder. This study examines the electrical transport properties of a single-layer MoS₂ field-effect transistor on a few-layered hBN substrate. Temperature-dependent transport measurements reveal that electrical conductivity is predominantly governed by a combination of simple activated and variable-range hopping mechanisms. The calculations on the experimental data yield a localization length around 5 nm for a typical defect density near the Fermi energy as 10¹⁴ eVcm^-2. Additionally, optoelectronic transport measurements exhibit temperature-dependent persistent photoconductivity, attributed to electron localization within defect states. Calculations based on the temperature-dependent photoconductivity relaxation indicate a localization length of 7 nm, suggesting a direct correlation between the two phenomena.