▎ 摘　　要

We report a technique to tune the excess charge concentration in single-layer graphene from p- to n-type up to densities of |n| similar to 1.2 x 10(13) cm(-2), corresponding to a displacement electric field of similar to 2.5 V/nm. The tuning is achieved by engineering the interaction between graphene and the underlying Si/SiO2 substrate with an amino group-terminated self-assembled monolayer, and subsequent rinsing in aqueous solutions at controlled pH. Raman spectroscopy and electrical measurements on treated graphene devices confirm the occurrence of doping. Interestingly, we found the field-effect mobility not to be significantly affected by the procedure. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim