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

doi:10.1021/nl4030787

paper

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

arXiv:1310.6428 · doi:10.1021/nl4030787

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 ( $E_{F} = \pm 0.35$ 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, $H = A (T_{e}^{3} - T_{l}^{3})$ . 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.

6 pages, 5 figures. Nano Letters, 2013

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

Abstract

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