1 research outputs found
Diffusive Charge Transport in Graphene on SiO2
We review our recent work on the physical mechanisms limiting the mobility of
graphene on SiO2. We have used intentional addition of charged scattering
impurities and systematic variation of the dielectric environment to
differentiate the effects of charged impurities and short-range scatterers. The
results show that charged impurities indeed lead to a conductivity linear in
density in graphene, with a scattering magnitude that agrees quantitatively
with theoretical estimates [1]; increased dielectric screening reduces
scattering from charged impurities, but increases scattering from short-range
scatterers [2]. We evaluate the effects of the corrugations (ripples) of
graphene on SiO2 on transport by measuring the height-height correlation
function. The results show that the corrugations cannot mimic long-range
(charged impurity) scattering effects, and have too small an
amplitude-to-wavelength ratio to significantly affect the observed mobility via
short-range scattering [3, 4]. Temperature-dependent measurements show that
longitudinal acoustic phonons in graphene produce a resistivity linear in
temperature and independent of carrier density [5]; at higher temperatures,
polar optical phonons of the SiO2 substrate give rise to an activated, carrier
density-dependent resistivity [5]. Together the results paint a complete
picture of charge carrier transport in graphene on SiO2 in the diffusive
regime.Comment: 28 pages, 7 figures, submitted to Graphene Week proceeding