Intrinsic carrier mobility of monolayer GeS and GeSe: First-principles calculation

Recently, novel two-dimensional (2D) semiconductors of GeS and GeSe have attracted attention due to their potential applications in future nanoelectronic devices. The carrier mobility is first calculated from deformation potential theory (DPT) based on longitudinal acoustic and optical phonon model. Three important parameters of effective mass, elastic modulus and deformation potential are analyzed. Then, the intrinsic mobility is calculated from EPC matrix element. If the polarization effect of semiconductor is considered in the calculation, the electron mobility of GeS (GeSe) is reduced to 4.07 × 101 cm2V−1s−1 (1.48 × 102 cm2V−1s−1) for x direction, and 1.94 × 101 cm2V−1s−1 (7.55 × 101 cm2V−1s−1) for y direction. The hole mobility is 4.77 × 101 cm2V−1s−1 (2.47 × 102 cm2V−1s−1) for x direction, and 1.52 × 101 cm2V−1s−1 (1.16 × 102 cm2V−1s−1) for y direction. It is found that longitudinal optical phonon scattering plays a decisive role in carrier mobility. In this study, we illustrate that DPT model from the longitudinal acoustic and optical phonon scattering will overestimate carrier mobility. Some factors that affect carrier mobility are revealed.