Regulation of Hot Electrons Transport Achieved through Controlled Electron-Phonon Coupling in Metallic Heterostructures

The electron-phonon (e-ph) interactions are pivotal in shaping the electrical and thermal properties, and in particular, determining the carrier dynamics and transport behaviors in optoelectronic devices. By employing pump-probe spectroscopy and ultrafast microscopy, the consequential role of e-ph coupling strength in the spatiotemporal evolution of hot electrons is elucidated. Thermal transport across the metallic interface is controlled to regulate effective e-ph coupling factor Geff in Au and Au/Cr heterostructure, and their impact on nonequilibrium transport of hot electrons is examined. Via the modulation of buried Cr thickness, a strong correlation between Geff and the diffusive behavior of hot electrons is found. By enhancing Geff through the regulation of thermal transport across interface, there is a significant reduction in e-ph thermalization time, the maximum diffusion length of hot electrons, and lattice heated area which are extracted from the spatiotemporal evolution profiles. Therefore, the increased Geff significantly weakens the diffusion of hot electrons and promotes heat relaxation of electron subsystems in both time and space. These insights propose a robust framework for spatiotemporal investigations of G impact on hot electron diffusion, underscoring its significance in the rational design of advanced optoelectronic devices with high efficiency. The effective electron-phonon coupling is readily modulated in metallic heterostructures by controlling thermal transport across the interface. By employing pump-probe spectroscopy and ultrafast microscopy, the enhanced electron-phonon coupling promotes heat relaxation of electron subsystems in both time and space is demonstrated. These findings highlight significant improvements in hot electrons transport in optoelectronic devices are anticipated with well-designed electron-phonon coupling. image