Surface polar phonon dominated electron transport in graphene

Abstract

Effect of chiral property on hot phonon distribution and energy loss rate due to surface polar phonons in a bilayer graphene J. Appl. Phys. 113, 063705 (2013); 10.1063/1.4790309Phonon-limited electron mobility in graphene calculated using tight-binding Bloch waves J. Appl. Phys. 112, 053702 (2012); 10.1063/1.4747930 Two-dimensional electron gases: Theory of ultrafast dynamics of electron-phonon interactions in graphene, surfaces, and quantum wellsThe effects of surface polar phonons on the electronic transport properties of monolayer graphene are studied by using a Monte Carlo simulation. Specifically, the low-field electron mobility and saturation velocity are examined for different substrates ͑SiC, SiO 2 , and HfO 2 ͒ in comparison to the intrinsic case. While the results show that the low-field mobility can be substantially reduced by the introduction of surface polar phonon scattering, corresponding degradation of the saturation velocity is not observed for all three substrates at room temperature. It is also found that surface polar phonons can influence graphene's electrical resistivity even at low temperature, leading potentially to inaccurate estimation of the acoustic phonon deformation potential constant.

Electron transport properties of bilayer graphene

“…A similar, positive impact of the substrate on the saturation velocity was also suggested in recent studies. 17,20,24 In BLG, the saturation velocity can reach 2.9 × 10 7 cm/s, which is about 1.5 times as large as the intrinsic value. Apparently, the enhancement of drift velocity is still prominent despite the stronger screening in BLG leading to smaller SPP scattering rates.…”

“…14,16,17 A similar treatment can be extended to BLG. By assuming that the electrons are equally distributed in the two layers of BLG, we can derive the corresponding scattering rate as…”

Unraveling the acoustic electron-phonon interaction in graphene

“…For example, samples with the commonly used SiO 2 substrate replaced by hexagonal boron nitride (h-BN) which has a lattice constant very close to that of graphene and an almost atomically flat surface with strongly reduced disorder, 12,13 have shown highly improved transport characteristics with mobilities approaching that of suspended graphene. 8,14,15 Furthermore, the high energy of the surface-optical phonons of h-BN results in a significant reduction of surface-optical phonon scattering [16][17][18] that for commonly used gate oxides starts to dominate the mobility around T ∼ 150-200 K. 5,7 When the mobility is dominated by acoustic phonon scattering, two transport regimes separated by the Bloch-Grüneisen (BG) temperature T BG = 2hk F c ph /k B can be identified. 19 Here, k F is the Fermi wave vector, c ph the sound velocity, and k B the Boltzmann constant (T BG ∼ 57 K √ n for the longitudinal acoustic phonon with the two-dimensional carrier density n measured in units of 10 12 cm −2 ).…”

Dielectric function and plasmons in graphene: A self-consistent-field calculation within a Markovian master equation formalism

“…Graphene plasmon modes have much shorter wave lengths than light with the same frequencies, and their propagation length is very sensitive to the damping pathways, such as intrinsic phonons [49][50][51] , ionized impurities [52][53][54] , and SO phonons on polar substrates [55][56][57] . The damping of graphene plasmons has been calculated based on the Mermin-Lindhard (ML) dielectric function 33 and its simplified version, the Drude dielectric function 40 .…”