Temperature-Dependent Transport in Suspended Graphene

The resistivity of ultraclean suspended graphene is strongly temperature (T) dependent for 5<T<240 K. At T-5 K transport is near-ballistic in a device of approximately 2 microm dimension and a mobility approximately 170,000 cm2/V s. At large carrier density, n>0.5 x 10(11) cm(-2), the resistivity increases with increasing T and is linear above 50 K, suggesting carrier scattering from acoustic phonons. At T=240 K the mobility is approximately 120,000 cm2/V s, higher than in any known semiconductor. At the charge neutral point we observe a nonuniversal conductivity that decreases with decreasing T, consistent with a density inhomogeneity <10(8) cm(-2).