First-Principles Calculations of the Strain-Tunable Carrier Mobility and Direct Band Gap in Hydrogenated CdSb Monolayers: Implications for Flexible Nanoelectronic and Optoelectronic Applications

We present first-principles density functional theory simulations on the hydrogenated CdSb monolayers under biaxial tensile strains. We demonstrate that full hydrogenation transforms the pristine metallic monolayer into a semiconductor with a direct band gap of 0.44 eV. Applying biaxial strains significantly affects the electronic structure of the hydrogenated CdSb monolayers, reducing the band gap to 0.016 eV at 4% strain with direct band gap nature preserved. The strain dependence of the band gap is analyzed by investigating the electronic energies of near-gap states and their bonding character. Additionally, we investigate the transport properties by computing the strain-modulated effective masses, deformation potential constants, and carrier mobilities of the hydrogenated CdSb monolayers. It is found that electron mobility is significantly enhanced with strain, particularly in the zigzag direction, whereas hole mobility shows less pronounced changes under similar conditions. At 0% strain, the highest carrier mobility is observed for holes along the zigzag direction at 2.26 × 10 3 cm 2 /(V s). At 4% strain, the highest carrier mobility is observed for electrons along the zigzag direction, reaching 8.16 × 10 3 cm 2 /(V s). Because of the strain tunability of the carrier mobility and direct band gap, our simulations suggest that the hydrogenated CdSb monolayers could have potential applications in nanoelectronic and optoelectronic devices, with strain engineering serving as an effective method to tune its physical properties.