Characterization of charge-carrier dynamics at the Bi2Se3/MgF2 interface by multiphoton pumped UV-Vis transient absorption spectroscopy

Glinka, Yuri D.1,2; He, Tingchao3; Sun, Xiao Wei1,4

2023-09-18

10.1088/1361-648X/acdc78

JOURNAL OF PHYSICS-CONDENSED MATTER   影响因子和分区

0953-8984

1361-648X

Separate relaxation dynamics of electrons and holes in experiments on optical pumping-probing of semiconductors is rarely observed due to their overlap. Here we report the separate relaxation dynamics of long-lived (similar to 200 mu s) holes observed at room temperature in a 10 nm thick film of the 3D topological insulator (TI) Bi2Se3 coated with a 10 nm thick MgF2 layer using transient absorption spectroscopy in the UV-Vis region. The ultraslow hole dynamics was observed by applying resonant pumping of massless Dirac fermions and bound valence electrons in Bi2Se3 at a certain wavelength sufficient for their multiphoton photoemission and subsequent trapping at the Bi2Se3/MgF2 interface. The emerging deficit of electrons in the film makes it impossible for the remaining holes to recombine, thus causing their ultraslow dynamics measured at a specific probing wavelength. We also found an extremely long rise time (similar to 600 ps) for this ultraslow optical response, which is due to the large spin-orbit coupling splitting at the valence band maximum and the resulting intervalley scattering between the splitting components. The observed dynamics of long-lived holes is gradually suppressed with decreasing Bi2Se3 film thickness for the 2D TI Bi2Se3 (film thickness below 6 nm) due to the loss of resonance conditions for multiphoton photoemission caused by the gap opening at the Dirac surface state nodes. This behavior indicates that the dynamics of massive Dirac fermions predominantly determines the relaxation of photoexcited carriers for both the 2D topologically nontrivial and 2D topologically trivial insulator phases.

carrier dynamics Bi2Se3 MgF2 interface transient absorption spectroscopy ultrafast

SCI ; EI

英语

第一 ; 通讯

Shenzhen Peacock Team Project[ZDSYS201707281632549] ; Shenzhen Key Laboratory for Advanced Quantum Dot Displays and Lighting[2016YFB0401702] ; null[KQTD2016030111203005]

Physics

Physics, Condensed Matter

WOS:001008373200001

IOP Publishing Ltd

20232714336475

Bismuth compounds ; Dynamics ; Film thickness ; Fluorine compounds ; Magnesium compounds ; Optical pumping ; Relaxation processes ; Selenium compounds ; Thick films ; Topology

Laser Applications:744.9 ; Combinatorial Mathematics, Includes Graph Theory, Set Theory:921.4 ; Mechanics:931.1

PHYSICS

Web of Science

1.Southern Univ Sci & Technol, Shenzhen Key Lab Adv Quantum Dot Displays & Lighti, Guangdong Univ Key Lab Adv Quantum Dot Displays &, Dept Elect & Elect Engn, Shenzhen 518055, Peoples R China
2.Natl Acad Sci Ukraine, Inst Phys, Kiev 03028, Ukraine
3.Shenzhen Univ, Coll Phys & Energy, Shenzhen 518060, Peoples R China
4.Shenzhen Planck Innovat Technol Pte Ltd, Shenzhen 518112, Peoples R China

Glinka, Yuri D.,He, Tingchao,Sun, Xiao Wei. Characterization of charge-carrier dynamics at the Bi2Se3/MgF2 interface by multiphoton pumped UV-Vis transient absorption spectroscopy[J]. JOURNAL OF PHYSICS-CONDENSED MATTER,2023,35(37).

Glinka, Yuri D.,He, Tingchao,&Sun, Xiao Wei.(2023).Characterization of charge-carrier dynamics at the Bi2Se3/MgF2 interface by multiphoton pumped UV-Vis transient absorption spectroscopy.JOURNAL OF PHYSICS-CONDENSED MATTER,35(37).

Glinka, Yuri D.,et al."Characterization of charge-carrier dynamics at the Bi2Se3/MgF2 interface by multiphoton pumped UV-Vis transient absorption spectroscopy".JOURNAL OF PHYSICS-CONDENSED MATTER 35.37(2023).