Strain-tunable inter-valley scattering defines universal mobility enhancement in n- and p-type 2D TMDs

TL;DR

This study reveals that strain-induced changes in inter-valley scattering, rather than effective mass, govern mobility enhancement in 2D TMD semiconductors, enabling significant performance improvements in electronic devices.

Contribution

It introduces a multiscale full-band transport model showing how biaxial strain modulates inter-valley scattering to enhance mobility in 2D TMDs, surpassing silicon strain effects.

Findings

Tensile strain increases n-type mobility via K-Q valley separation.

Compressive strain improves p-type mobility through Γ-K decoupling.

Model predictions match experimental measurements across various conditions.

Abstract

Strain fundamentally alters carrier transport in semiconductors by modifying their band structure and scattering pathways. In transition-metal dichalcogenides (TMDs), an emerging class of 2D semiconductors, we show that mobility modulation under biaxial strain is dictated by changes in inter-valley scattering rather than effective mass renormalization as in bulk silicon. Using a multiscale full-band transport framework that incorporates both intrinsic phonon, extrinsic impurity, and dielectric scattering, we find that tensile strain enhances n-type mobility through K-Q valley separation, while compressive strain improves p-type mobility via {\Gamma}-K decoupling. The tuning rates calculated from our full-band model far exceed those achieved by strain engineering in silicon. Both relaxed and strain-modulated carrier mobilities align quantitatively with experimentally verified measurements and are valid across a wide range of practical FET configurations. The enhancement remains robust across variations in temperature, carrier density, impurity level, and dielectric environment. Our results highlight the pivotal role of strain in improving the reliability and performance of 2D TMD-based electronics.