Computational quest for high-mobility 2D materials*

Recently, we identified close to 2000 exfoliable 2D materials from first-principles calculations [1]. The next natural step is to explore their properties and look for novel or improved performance. Here, we are searching for electrostatically-doped 2D semiconductors with superior electronic transport properties.

A first goal is then to develop accurate and systematic workflows to compute phonon-limited mobilities [2]. These workflows identify the pockets of electronic states relevant to transport and the phonons needed to describe all possible scattering events within these pockets. Electron-phonon couplings are computed using density-functional perturbation theory with the appropriate 2D boundary conditions and gates to induce doping [3]. Notably, this comprehensive approach to electron-phonon scattering reveals the consistently large intervalley scattering and the subtle impact of doping on electron-phonon interactions. Finally, mobilities are obtained by solving the Boltzmann transport equation using an iterative scheme, combined with an exact integration of the delta functions associated with energy conservation.


Computing the mobility of all the materials in the database remains impractical. Instead, we learn the key features that characterize a high mobility 2D material from a first in-depth study of a small but diverse selection of materials. Density of states, carrier velocities, number of valleys, phonon energetics as well as intra- and inter-valley electron-phonon interactions all play a role. We then translate these observations into computationally affordable and quantifiable descriptors to identify the best candidates in the database.

[1] N. Mounet et al., Nature Nanotechnology 13, 246 (2018).
[2] T. Sohier, D. Campi, N. Marzari, and M. Gibertini, arXiv:1808.10808 (2018)
[3] T. Sohier, M. Calandra, and F. Mauri, Physical Review B 96, 075448 (2017).