Sub-µm Hot Carrier Diffusion in 2D MoS2 on High-κ Metal-Oxide Substrate.

Harnessing the potential of hot carriers is a promising approach for advancing the efficiency of photovoltaic and optoelectronic devices. However, their rapid energy dissipation through carrier-phonon scattering and recombination significantly limits practical applications. Dielectric engineering has emerged as a promising strategy to modulate carrier transport properties in low-dimensional materials, including transition metal dichalcogenides. In this study, the impact of dielectric screening is investigated on hot carrier dynamics in monolayer MoS₂ using transient absorption microscopy. The results demonstrate that a high dielectric constant (high-κ) metal-oxide substrate effectively suppresses the Coulomb potential, reducing carrier scattering and recombination while significantly enhancing hot carrier diffusion length and coefficient compared to a conventional quartz substrate. These findings establish dielectric engineering as a powerful tool for improving hot carrier transport without requiring complex material modifications or external stimuli, offering a scalable and efficient strategy for next-generation electronic and optoelectronic devices.