We demonstrate by experiments and numerical simulations that the low-temperature current-voltage characteristics in diffusive bilayer graphene (BLG) exhibit a strong superlinearity at finite bias voltages. The superlinearity is weakly dependent on doping and on the length of the graphene sample. This effect can be understood as a result of Joule heating. It is stronger in BLG than in monolayer graphene (MLG), since the conductivity of BLG is more sensitive to temperature due to the higher density of electronic states at the Dirac point.
Abstract:Atomic layer deposition of HfO 2 on unmodified graphene from HfCl 4 and H 2 O was investigated. Surface RMS roughness down to 0.5 nm was obtained for amorphous, 30 nm thick hafnia film grown at 180°C. HfO 2 was also deposited in a two-step temperature process where the initial growth of about 1 nm at 170°C was continued up to 10-30 nm at 300°C. This process yielded uniform, monoclinic HfO 2 films with RMS roughness of 1.7 nm for 10-12 nm thick films and 2.5 nm for 30 nm thick films. Raman spectroscopy studies revealed that the deposition process caused compressive biaxial strain in graphene, whereas no extra defects were generated. An 11 nm thick HfO 2 film deposited onto bilayer graphene reduced the electron mobility by less than 10% at the Dirac point and by 30-40% far away from it.PACS (2008)
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.