Enhancement of carrier lifetime by spin-orbit coupling in a topological insulator of an Sb2Te3 thin film

Hyejin Choi, Seonghoon Jung, Tae Hyeon Kim, Jimin Chae, Hanbum Park, KwangHo Jeong, Jaehun Park, Mann-Ho Cho

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Electrons and phonons in chalcogenide-based materials are important factors in the performance of optical data-storage media and thermoelectric devices. However, the fundamental kinetics of carriers in chalcogenide materials remains controversial, and active debate continues over the mechanism responsible for carrier relaxation. In this study, we used optical-pump terahertz-probe spectroscopy, which permits the relationship between structural phase transition and optical property transitions to be examined, to investigate the ultrafast carrier dynamics in a multilayered [Sb(3 Å)/Te(9 Å)]n thin film during the transition from the disordered to crystalline phase. Using terahertz time-domain spectroscopy and a contact-free optical technique, we demonstrated that the optical conductance and carrier concentration vary as functions of annealing temperature. Moreover, we observed that the topological surface state (TSS) affects the enhancement of the carrier lifetime, which is closely related to the degree of spin-orbit coupling (SOC). The combination of the optical technique and proposed carrier relaxation mechanism provides a powerful tool for monitoring TSS and SOC. Consequently, it was determined that the response of the disordered phase is dominated by an electron-phonon coupling effect, while that of the crystalline structure is controlled by a Dirac surface state and SOC effects. These results are important for understanding the fundamental physics of phase change materials and for optimizing and designing materials with better performance in optoelectronic devices.

Original languageEnglish
Pages (from-to)19025-19035
Number of pages11
JournalNanoscale
Volume8
Issue number45
DOIs
Publication statusPublished - 2016 Dec 7

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Carrier lifetime
Surface states
Orbits
Thin films
Spectroscopy
Crystalline materials
Optical data storage
Phase change materials
Electrons
Phonons
Optoelectronic devices
Carrier concentration
Physics
Optical properties
Phase transitions
Pumps
Annealing
Kinetics
Monitoring
Temperature

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

Cite this

Choi, Hyejin ; Jung, Seonghoon ; Kim, Tae Hyeon ; Chae, Jimin ; Park, Hanbum ; Jeong, KwangHo ; Park, Jaehun ; Cho, Mann-Ho. / Enhancement of carrier lifetime by spin-orbit coupling in a topological insulator of an Sb2Te3 thin film. In: Nanoscale. 2016 ; Vol. 8, No. 45. pp. 19025-19035.
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abstract = "Electrons and phonons in chalcogenide-based materials are important factors in the performance of optical data-storage media and thermoelectric devices. However, the fundamental kinetics of carriers in chalcogenide materials remains controversial, and active debate continues over the mechanism responsible for carrier relaxation. In this study, we used optical-pump terahertz-probe spectroscopy, which permits the relationship between structural phase transition and optical property transitions to be examined, to investigate the ultrafast carrier dynamics in a multilayered [Sb(3 {\AA})/Te(9 {\AA})]n thin film during the transition from the disordered to crystalline phase. Using terahertz time-domain spectroscopy and a contact-free optical technique, we demonstrated that the optical conductance and carrier concentration vary as functions of annealing temperature. Moreover, we observed that the topological surface state (TSS) affects the enhancement of the carrier lifetime, which is closely related to the degree of spin-orbit coupling (SOC). The combination of the optical technique and proposed carrier relaxation mechanism provides a powerful tool for monitoring TSS and SOC. Consequently, it was determined that the response of the disordered phase is dominated by an electron-phonon coupling effect, while that of the crystalline structure is controlled by a Dirac surface state and SOC effects. These results are important for understanding the fundamental physics of phase change materials and for optimizing and designing materials with better performance in optoelectronic devices.",
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Enhancement of carrier lifetime by spin-orbit coupling in a topological insulator of an Sb2Te3 thin film. / Choi, Hyejin; Jung, Seonghoon; Kim, Tae Hyeon; Chae, Jimin; Park, Hanbum; Jeong, KwangHo; Park, Jaehun; Cho, Mann-Ho.

In: Nanoscale, Vol. 8, No. 45, 07.12.2016, p. 19025-19035.

Research output: Contribution to journalArticle

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