Coherent surface-to-bulk vibrational coupling in the 2D topologically trivial insulator Bi₂Se₃ monitored by ultrafast transient absorption spectroscopy.

ABSTRACT: Ultrafast carrier relaxation in the 2D topological insulator (TI) Bi₂Se₃ [gapped Dirac surface states (SS)] and how it inherits ultrafast relaxation in the 3D TI Bi₂Se₃ (gapless Dirac SS) remains a challenge for developing new optoelectronic devices based on these materials. Here ultrashort (~ 100 fs) pumping pulses of ~ 340 nm wavelength (~ 3.65 eV photon energy) were applied to study ultrafast electron relaxation in the 2D TI Bi₂Se₃ films with a thickness of 2 and 5 quintuple layers (~ 2 and ~ 5 nm, respectively) using transient absorption (TA) spectroscopy in the ultraviolet-visible spectral region (1.65-3.9 eV). The negative and positive contributions of TA spectra were attributed to absorption bleaching that mostly occu

SUBMITTER: Glinka YD 

PROVIDER: S-EPMC8933573 | biostudies-literature | 2022 Mar

REPOSITORIES: biostudies-literature