Profiling novel high-conductivity 2D semiconductors

TL;DR

This paper identifies and analyzes 11 2D semiconductors with high electrical conductivity driven by electron-phonon interactions, using advanced computational methods to discover new promising materials for electronic applications.

Contribution

The study combines density-functional perturbation theory and Boltzmann transport calculations to identify novel high-conductivity 2D semiconductors from a large database, highlighting the importance of electron-phonon scattering features.

Findings

Several high-conductivity 2D materials identified, including recent and novel compounds.

Electron-phonon interaction strength and anisotropy significantly influence transport performance.

Limitations of band property-based selection methods are demonstrated.

Abstract

When complex mechanisms are involved, pinpointing high-performance materials within large databases is a major challenge in materials discovery. We focus here on phonon-limited conductivities, and study 2D semiconductors doped by field effects. Using state-of-the-art density-functional perturbation theory and Boltzmann transport equation, we discuss 11 monolayers with outstanding transport properties. These materials are selected from a computational database of exfoliable materials providing monolayers that are dynamically stable and that do not have more than 6 atoms per unit cell. We first analyse electron-phonon scattering in two well-known systems: electron-doped InSe and hole-doped phosphorene. Both are single-valley systems with weak electron-phonon interactions, but they represent two distinct pathways to fast transport: a steep and deep isotropic valley for the former and strongly anisotropic electron-phonon physics for the latter. We identify similar features in the database and compute the conductivities of the relevant monolayers. This process yields several high-conductivity materials, some of them only very recently emerging in the literature (GaSe, Bi$_2$SeTe$_2$, Bi$_2$Se$_3$, Sb$_2$SeTe$_2$), others never discussed in this context (AlLiTe$_2$, BiClTe, ClGaTe, AuI). Comparing these 11 monolayers in detail, we discuss how the strength and angular dependency of the electron-phonon scattering drives key differences in the transport performance of materials despite similar valley structure. We also discuss the high conductivity of hole-doped WSe$_2$, and how this case study shows the limitations of a selection process that would be based on band properties alone.