New insights into layer-dependent carrier dynamics of LPCVD grown graphene from terahertz spectroscopy

The carrier dynamics in graphene is highly sensitive to layer number, making systematic layer-dependent studies essential for understanding the fundamental properties of graphene and for engineering tunable quantum devices. However, precisely probing and quantifying these layer-specific carrier dynamics remains a significant challenge, necessitating advanced spectroscopic approaches. Herein, a comprehensive and unprecedented investigation of layer-dependent carrier dynamics in single layer, bilayer and trilayer graphene is presented using terahertz spectroscopy, supported by first-principles band structures and density of states that elucidate the underlying mechanism. The study reveals a systematic evolution of the intra-band carrier momentum relaxation time, scattering rate and mobility with increasing number of graphene layers through terahertz-time domain spectroscopy, highlighting the impact of layer variation on the carrier dynamics. The study further reveals the occurrence of extended carrier relaxation lifetimes after optical pumping in bilayer and trilayer graphene, offering key insights into carrier relaxation. This work provides experimental evidence of carrier dynamics variation of graphene with each atomic layer thereby establishing a new benchmark for precision in probing low-energy carrier dynamics and highlighting its significant implications for spectroscopic and optoelectronic applications.