石墨烯
材料科学
太赫兹辐射
电导率
载流子散射
放松(心理学)
德鲁德模型
螺旋钻
俄歇效应
凝聚态物理
氧化物
分子物理学
渗透(认知心理学)
饱和(图论)
散射
化学物理
光电子学
原子物理学
纳米技术
化学
光学
物理
神经科学
物理化学
冶金
组合数学
生物
社会心理学
数学
心理学
作者
Jaeseok Kim,Ji Hye Oh,Chihun In,Yun Shik Lee,Theodore B. Norris,Seong Chan Jun,Hyunyong Choi
出处
期刊:ACS Nano
[American Chemical Society]
日期:2014-02-10
卷期号:8 (3): 2486-2494
被引量:29
摘要
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.
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