Interfacial icelike water local doping of graphene†
Charge transfer at interfaces plays a critical role in the performance of graphene based electronic devices. However, separate control of the charge transfer process in the graphene/SiO2 system is still challenging. Herein, we investigate the effects of the trapped interfacial icelike water layer on the charge transfer between graphene and the SiO2/Si substrate through recording the surface potential changes induced by partial removal of the interfacial icelike water layer upon in situ heating. The scanning Kelvin probe microscopy surface potential mapping shows that the graphene is electronically modified by the icelike water layer as the electron density transfers from graphene to the icelike water layer, resulting in hole-doping of graphene, which was also confirmed by the graphene field effect transistor electrical transport measurements. In addition, the density functional calculations provide in-depth insight into the electronic contributions of the icelike water layer to graphene and the charge transfer mechanism. This research will improve our ability to manipulate graphene's electronic properties for diverse applications, such as humidity sensing.