Observation of thickness-independent ultrafast relaxation times in MPCVD few-layer graphene

IF 11.6 2区材料科学 Q1 CHEMISTRY, PHYSICAL Carbon Pub Date : 2024-10-18 DOI:10.1016/j.carbon.2024.119700

Tânia M. Ribeiro , Tiago E.C. Magalhães , Bohdan Kulyk , Alexandre F. Carvalho , Sebastian Nilsson , Henrik Feuk , António J.S. Fernandes , Florinda Costa , Paulo T. Guerreiro , Helder Crespo

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Abstract

Graphene presents unique optoelectronic properties, making it attractive for the development of a wide range of new and advanced technological applications such as high-speed photodetectors and all-optical modulators. The study and control of the generated carriers in graphene, namely their ultrafast relaxation dynamics, are of great importance for these applications. Here, we report the ultrafast relaxation times of photogenerated carriers in few-layer graphene grown by microwave plasma chemical vapour deposition. Graphene samples with 3, 5 and 6 layers were studied by degenerate femtosecond optical pump-probe spectroscopy. We observed a fast relaxation constant on the order of

120 - 180 fs

and a slow relaxation constant below 1 ps, associated with carrier-carrier scattering and carrier-phonon scattering processes, respectively. These results suggest that small variations in the number of graphene layers do not affect the dynamics.

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在 MPCVD 少层石墨烯中观测到与厚度无关的超快弛豫时间

石墨烯具有独特的光电特性，使其在开发高速光电探测器和全光调制器等各种新型先进技术应用方面具有吸引力。研究和控制石墨烯中产生的载流子，即它们的超快弛豫动力学，对这些应用具有重要意义。在这里，我们报告了通过微波等离子体化学气相沉积法生长的少层石墨烯中光生载流子的超快弛豫时间。我们采用变性飞秒光学泵浦探针光谱法研究了 3 层、5 层和 6 层石墨烯样品。我们观察到一个 120-180fs 量级的快速弛豫常数和一个低于 1 ps 的慢速弛豫常数，它们分别与载流子-载流子散射和载流子-声子散射过程有关。这些结果表明，石墨烯层数的微小变化不会影响动力学。

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来源期刊

Carbon 工程技术-材料科学：综合

CiteScore

20.80

自引率

7.30%

发文量

审稿时长

23 days

期刊介绍： The journal Carbon is an international multidisciplinary forum for communicating scientific advances in the field of carbon materials. It reports new findings related to the formation, structure, properties, behaviors, and technological applications of carbons. Carbons are a broad class of ordered or disordered solid phases composed primarily of elemental carbon, including but not limited to carbon black, carbon fibers and filaments, carbon nanotubes, diamond and diamond-like carbon, fullerenes, glassy carbon, graphite, graphene, graphene-oxide, porous carbons, pyrolytic carbon, and other sp2 and non-sp2 hybridized carbon systems. Carbon is the companion title to the open access journal Carbon Trends. Relevant application areas for carbon materials include biology and medicine, catalysis, electronic, optoelectronic, spintronic, high-frequency, and photonic devices, energy storage and conversion systems, environmental applications and water treatment, smart materials and systems, and structural and thermal applications.