Graphene field effect transistors using TiO2 as the dielectric layer

In this work, we report the electron mobility and electron density of three graphene field effect transistors using a 280 nm titanium dioxide dielectric layer and a graphene channel of area 300 × 300 μm2. We achieve electron mobilities up to 1877 cm2/V and the Dirac point appears in small gate voltages, as compared to similar SiO2 transistors. Also, we obtain the TiO2 surface roughness through profilometry and confirm that electron mobility is inversely proportional to the channel's surface roughness. •High room temperature mobility in graphene field effect transistors with TiO2 as the dielectric layer.•The electron mobility is inversely proportional to the substrate's roughness.•Small voltages are needed to achieve the ambipolar effect in graphene field effect transistors made with TiO2.