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He Lin Zhao

Publications and source records attributed to He Lin Zhao.

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Enhancing Hole Mobility in Monolayer $WSe_{2}$ p-FETs via Process-Induced Compression

Understanding the interactions between strain, interfacial mechanics, and electrical performance is critical for designing beyond silicon electronics based on hetero-integrated 2D materials. Through combined experiment and simulation, we demonstrated and analyzed the enhancement of hole mobility in p-type monolayer $WSe_{2}$ field effect transistors (FETs) under biaxial compression. We tracked FET performance versus strain by incrementing compressive strain to $WSe_{2}$ channels via sequential AlOx deposition and performing intermediate photoluminescence and transport measurements. The hole mobility factor increased at a rate of 340 $\pm$ 95 %/%$\epsilon$, and the on-current factor increased at a rate of 460 $\pm$ 340 %/%$\epsilon$. Simulation revealed that the enhancement under compression arises primarily from a reduction in inter-valley scattering between the $\Gamma$--K valence bands, and the rate is robust against variations in carrier density, impurity density, or dielectric environment. These findings show that compressive strain is a powerful technique for enhancing performance in 2D p-FETs and that it is multiplicative with defect and doping engineering.

cond-mat.mtrl-sci

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

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.

physics.app-ph