Unconventional terahertz carrier relaxation in Graphene oxide: Observation of enhanced auger recombination due to defect saturation

Jaeseok Kim, Juyeong Oh, Chihun In, Yun Shik Lee, Theodore B. Norris, Seong Chan Jun, Hyunyong Choi

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Photoexcited carrier relaxation is a recurring topic in understanding the transient conductivity dynamics of graphene-based devices. For atomically thin graphene oxide (GO), a simple free-carrier Drude response is expected to govern the terahertz (THz) conductivity dynamics-same dynamics observed in conventional CVD-grown graphene. However, to date, no experimental testimony has been provided on the origin of photoinduced conductivity increase in GO. Here, using ultrafast THz spectroscopy, we show that the photoexcited carrier relaxation in GO exhibits a peculiar non-Drude behavior. Unlike graphene, the THz dynamics of GO show percolation behaviors: as the annealing temperature increases, transient THz conductivity rapidly increases and the associated carrier relaxation changes from mono- to biexponential decay. After saturating the recombination decay through defect trapping, a new ultrafast decay channel characterized by multiparticle Auger scattering is observed whose threshold pump fluence is found to be 50 μJ/cm2. The increased conductivity is rapidly suppressed within 1 ps due to the Auger recombination, and non-Drude THz absorptions are subsequently emerged as a result of the defect-trapped high-frequency oscillators.

Original languageEnglish
Pages (from-to)2486-2494
Number of pages9
JournalACS Nano
Volume8
Issue number3
DOIs
Publication statusPublished - 2014 Mar 25

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All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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