Résumé
Thousands of novel 2D materials have been predicted from first-principles, offering exciting perspectives for the design of high-performance electronic devices. We focus here on intrinsic, phonon-limited transport in semiconductors and start from the Materials Cloud's database of 256 exfoliable materials with less than 6 atoms per unit cell. The most conductive layers are identified by establishing desirable band features based on 2 well-known high-conductivity semiconductors (Phosphorene and InSe). The best candidates are selected, and their conductivity is computed using density-functional perturbation theory and the Boltzmann transport equation. Calculations are done in highly-doped systems, with carrier densities of 10ˆ13 cm-2 induced by field effect. The selected materials' outstanding transport properties are explained via a thorough analysis of electron-phonon scattering (1).
Building on the insights gained in the process, we then discuss pathways to engineer high conductivity in 2D layers with otherwise limited performances. Supported by first-principle calculations, electron-phonon scattering is shown to be suppressed via two mechanisms. Valley-engineering consists in eliminating intervalley scattering by shifting the valleys in energy, using strain or other symmetry-breaking perturbations in selected materials (2). Remote screening designates the screening of electron-phonon interactions in the semiconductor from a neighboring metallic layer within a van der Waals heterostructure, and it is particularly e cient in materials where the Fröhlich interaction dominates (3).