Ultrafast dynamics of hot electrons and phonons in chemical vapor deposited graphene

Kuan Chun Lin, Ming Yang Li, Lain-Jong Li, D. C. Ling, C. C. Chi, Jeng Chung Chen

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

The relaxation dynamics of photoexcited carriers in a chemical vapor deposited graphene transferred on quartz substrate has been investigated by using ultrafast optical-pump terahertz (THz)-probe spectroscopy. Terahertz transmission through graphene sample is reduced by optical pumping. The change of transmission decays exponentially after the optical pulse. We find the relaxation time is insensitive to the substrate temperature from 10 K to 300 K but increases sublinearly with pump fluence. We model the relaxation process involving electron-phonon coupling together with a set of rate equations to describe the transient responses of quasi-particles and optical phonons. The increases of the extracted carrier temperature and the measured relaxation time with pump fluence are associated with the fact that high pump fluence significantly increases the carrier temperature and broadens the carrier distribution. As a result, it leads to the reduction of optical phonon emission efficiency and the decrease of cooling rate as well.

Original languageEnglish (US)
Article number133511
JournalJournal of Applied Physics
Volume113
Issue number13
DOIs
StatePublished - Apr 7 2013

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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