Shot noise and conductivity at high bias in bilayer graphene

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Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2011-12-14
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Language
en
Pages
7
1-7
Series
PHYSICAL REVIEW B, Volume 84, issue 24
Abstract
We have studied electronic conductivity and shot noise of bilayer graphene (BLG) sheets at high bias voltages and low bath temperature T 0=4.2 K. As a function of bias, we find initially an increase of the differential conductivity, which we attribute to self-heating. At higher bias, the conductivity saturates and even decreases due to backscattering from optical phonons. The electron-phonon interactions are also responsible for the decay of the Fano factor at bias voltages V>0.1 V. The high bias electronic temperature has been calculated from shot-noise measurements, and it goes up to ∼1200 K at V=0.75 V. Using the theoretical temperature dependence of BLG conductivity, we extract an effective electron-optical phonon scattering time τ e-op. In a 230-nm-long BLG sample of mobility μ=3600 cm2V -1s -1, we find that τ e-op decreases with increasing voltage and is close to the charged impurity scattering time τ imp=60 fs at V=0.6 V.
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Fay , A , Danneau , R , Viljas , J K , Wu , F , Tomi , M Y , Wengler , J , Wiesner , M & Hakonen , P J 2011 , ' Shot noise and conductivity at high bias in bilayer graphene : Signatures of electron-optical phonon coupling ' , Physical Review B , vol. 84 , no. 24 , 245427 , pp. 1-7 . https://doi.org/10.1103/PhysRevB.84.245427