TITLE:
Anisotropic Electron-Phonon Coupling in Fluorinated GeC: Ultra-Fast Hot-Carrier Thermalization from First Principles
AUTHORS:
N’goyé Bré-Junior Kanga, Boris Irie-Bi, Lalla Btissam Drissi, Abdelali Ait Taleb
KEYWORDS:
Electron-Phonon Coupling, Fluorination, 2D Binary Monolayer, Linewidth, Relaxation Time, Thermalization, Scattering Rate
JOURNAL NAME:
Journal of Materials Science and Chemical Engineering,
Vol.14 No.3,
March
12,
2026
ABSTRACT: Ultra-fast hot-carrier relaxation via electron-phonon (e-ph) coupling fundamentally limits efficiency in optoelectronic devices. This ab initio study employs density functional theory (DFT) and many-body perturbation theory to probe these dynamics in the fully fluorinated GeC (F-GeC-F) monolayer, a wide-gap 2D semiconductor with exceptional stability. Our calculations show that optical phonons dominate electron-phonon scattering, with the LO2 mode governing the VBM and the LO3 mode dominating the CBM, where scattering is significantly stronger, making LO3 the primary channel overall. This strong coupling drives ultra-fast thermalization 100 fs across 0 - 400 K, matching unfluorinated GeC despite fluorination’s dramatic bandgap expansion. Pronounced anisotropy emerges in linewidths along high-symmetry k-paths, with coupling strength varying dramatically by crystallographic direction and temperature. These mode-resolved, temperature-dependent insights, nearly impossible to isolate experimentally, offer a microscopic blueprint for engineering carrier lifetimes in next-generation 2D nanoelectronics and photodetectors.