A SiO2/Si substrate modified by an octadecyltrimethoxysilane (OTMS) self-assembled monolayer is used to obtain high-quality graphene devices with low intrinsic doping level. The carrier mobility can reach 47 000 cm(2) V-1 s(-1). The findings will pave the way for approaching the intrinsic properties of supported graphene, elucidating the scattering origins, and gaining a better understanding of the mechanism of carrier transport in graphene.