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arXiv · 1310.6428

Transient absorption and photocurrent microscopy show hot electron supercollisions describe the rate-limiting relaxation step in graphene

Matt W. Graham·Su-Fei Shi·Zenghui Wang·Daniel C. Ralph·Jiwoong Park·Paul L. McEuen
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Abstract

Using transient absorption (TA) microscopy as a hot electron thermometer we show disorder-assisted acoustic-phonon supercollisions (SCs) best describes the rate-limiting relaxation step in graphene over a wide range of lattice temperatures ($T_l=$5-300 K), Fermi energies ($E_F=\pm0.35$ eV), and optical probe energies (~0.3 - 1.1 eV). Comparison with simultaneously collected transient photocurrent, an independent hot electron thermometer, confirms the rate-limiting optical and electrical response in graphene are best described by the SC-heat dissipation rate model, $H=A(T^3_e- T^3_l)$. Our data further shows the electron cooling rate in substrate supported graphene is twice as fast as in suspended graphene sheets, consistent with SC-model prediction for disorder.

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Matt W. Graham, Su-Fei Shi, Zenghui Wang, Daniel C. Ralph, Jiwoong Park, Paul L. McEuen. 2013-10-23. Transient absorption and photocurrent microscopy show hot electron supercollisions describe the rate-limiting relaxation step in graphene. https://doi.org/10.1021/nl4030787

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