▎ 摘　　要

We show that graphene device could be controllably doped by the bottom substrate by inserting atomic layer deposition grown ZnO between graphene and SiO2 substrate. To clarify the effect of bottom ZnO, length of the graphene transistor channel was varied from 20 to 200 Lim, while that of ZnO was fixed to 10 Lim. Graphene devices supported on ZnO film show marked difference from those supported on SiO2 substrates; bottom ZnO layer behave as an electron donor. UV illumination experiment on hybrid graphene-ZnO device reveals that the effect of doping from ZnO becomes negligible when the graphene channel length made about four times larger than that of ZnO stripe. (C) 2016 Elsevier B.V. All rights reserved.