Structural and electronic characterization of graphene grown by chemical vapor deposition and transferred onto sapphire

•CVD graphene is transferred onto sapphire.•Transport measurements reveal relatively low charge carriers mobility.•Scanning probe microscopy experiments reveal the presence of robust contaminant layers between the graphene and the sapphire, responsible for the low carriers mobility. We present a combination of magnetotransport and local probe measurements on graphene grown by chemical vapor deposition on copper foil and subsequently transferred onto a sapphire substrate. A rather strong p-doping is observed (∼9×1012cm−2) together with quite low carrier mobility (∼1350cm2/Vs). Atomic force and tunneling imaging performed on the transport devices reveals the presence of contaminants between sapphire and graphene, explaining the limited performance of our devices. The transferred graphene displays ridges similar to those observed whilst graphene is still on the copper foil. We show that, on sapphire, these ridges are made of different thicknesses of the contamination layer and that, contrary to what was reported for hBN or certain transition metal dichalcogenides, no self-cleansing process of the sapphire substrate is observed.