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We investigate theoretically the impact of the dielectric environment on electronic transport in transition metal dichalcogenide monolayers. The low-field carrier mobility in free-standing layers is calculated using well-known ab initio methods, and the study is extended to layers in double-gate structures using the dielectric continuum approximation. In particular, we account for the screening of the electron–phonon interaction by the free carriers in the layer and by the dielectric environment. In addition, we include scattering with the hybrid interface optical-phonon/plasmon excitations ("remote phonons"). We find that whereas the presence of insulators with a high dielectric constant may increase the carrier mobility when ignoring the latter process, scattering with the hybrid interface excitations negates this beneficial effects and depresses the mobility significantly below its value in free-standing monolayers. [ABSTRACT FROM AUTHOR]

The absence of a band gap in graphene makes it of minor interest for field-effect transistors. Layered metal chalcogenides have shown great potential in device applications thanks to their wide bandgap and high carrier mobility. Interestingly, in the ever-growing library of two-dimensional (2D) materials, monolayer InSe appears as one of the new promising candidates, although still in the initial stage of theoretical studies. Here, we present a theoretical study of this material using density functional theory (DFT) to determine the electronic band structure as well as the phonon spectrum and electron-phonon matrix elements. The electron-phonon scattering rates are obtained using Fermi's Golden Rule and are used in a full-band Monte Carlo computer program to solve the Boltzmann transport equation (BTE) to evaluate the intrinsic low-field mobility and velocity-field characteristic. The electron-phonon matrix elements, accounting for both long- and short-range interactions, are considered to study the contributions of different scattering mechanisms. Since monolayer InSe is a polar piezoelectric material, scattering with optical phonons is dominated by the long-range interaction with longitudinal optical (LO) phonons while scattering with acoustic phonons is dominated by piezoelectric scattering with the longitudinal (LA) branch at room temperature (T = 300 K) due to a lack of a center of inversion symmetry in monolayer InSe. The low-field electron mobility, calculated considering all electron-phonon interactions, is found to be 110 cm2V−1s−1, whereas values of 188 cm2V−1s−1 and 365 cm2V−1s−1 are obtained considering the long-range and short-range interactions separately. Therefore, the calculated electron mobility of monolayer InSe seems to be competitive with other previously studied 2D materials and the piezoelectric properties of monolayer InSe make it a suitable material for a wide range of applications in next generation nanoelectronics. [ABSTRACT FROM AUTHOR]