Transport Study of Charge Carrier Scattering in Monolayer WSe$_2$

TL;DR

This study investigates charge carrier scattering in high-quality monolayer WSe$_2$ transistors, revealing non-monotonic mobility behavior and demonstrating quantized conductance, which highlights the potential for advanced quantum optoelectronic applications.

Contribution

It provides the first detailed quantum transport analysis of defect-related scattering in monolayer WSe$_2$, linking energy-dependent scattering to mobility behavior and demonstrating device quality through quantized conductance.

Findings

Non-monotonic mobility as a function of hole density.

Energy-dependent scattering amplitude explains mobility behavior.

Observation of quantized conductance steps in quantum point contacts.

Abstract

Employing flux-grown single crystal WSe$_2$, we report charge carrier scattering behaviors measured in $h$-BN encapsulated monolayer field effect transistors. We perform quantum transport measurements across various hole densities and temperatures and observe a non-monotonic change of transport mobility $\mu$ as a function of hole density in the degenerately doped sample. This unusual behavior can be explained by energy dependent scattering amplitude of strong defects calculated using the T-matrix approximation. Utilizing long mean-free path ($>$500 nm), we demonstrate the high quality of our electronic devices by showing quantized conductance steps from an electrostatically-defined quantum point contact. Our results show the potential for creating ultra-high quality quantum optoelectronic devices based on atomically thin semiconductors.