Electron and hole transport in disordered monolayer MoS2: atomic vacancy-induced short-range and Coulomb disorder scattering

TL;DR

This study investigates how atomic vacancies in monolayer MoS2 affect electron and hole transport, revealing the dominant role of Coulomb disorder in limiting low-temperature mobility and the impact of vacancy charge states.

Contribution

It provides a detailed theoretical analysis of vacancy-induced scattering, highlighting the renormalization of short-range scattering and the dominance of Coulomb disorder in TMDs.

Findings

Charged vacancies lead to Coulomb-disorder dominated scattering.

Neutral vacancies result in higher mobility and unique density dependence.

Strong energy dependence of scattering rate due to vacancy effects.

Abstract

Atomic disorder is a common limiting factor for the low-temperature mobility in monolayer transition-metal dichalcogenides (TMDs; MX2). Here, we study the effect of often occurring atomic vacancies on carrier scattering and transport in p- and n-type monolayer MoS2. Due to charge trapping in vacancy-induced in-gap states, both neutral and charged vacancies resembling, respectively, short-range and combined short-range and long-range Coulomb scatterers, must be considered. Using the T-matrix formalism, we demonstrate a strong renormalization of the Born description of short-range scattering, manifested in a pronounced reduction and a characteristic energy dependence of the scattering rate. As a consequence, carrier scattering in TMDs with charged vacancies is dominated by the long-range Coulomb-disorder scattering, giving rise to a strong screening-induced temperature and density dependence of the low-temperature carrier mobility. For TMDs with neutral vacancies, the absence of intrinsic Coulomb disorder results in significantly higher mobilities as well as an unusual density dependence of the mobility which decreases with the carrier density. Our work illuminates the transport-limiting effects of atomic-vacancy scattering relevant for high-mobility TMD devices.