Tunable Graphene Electronics with Local Ultrahigh Pressure

• Published in: Advanced functional materials Vol. 29; no. 8
• Main Authors: Ares, Pablo, Pisarra, Michele, Segovia, Pilar, Díaz, Cristina, Martín, Fernando, Michel, Enrique G., Zamora, Félix, Gómez‐Navarro, Cristina, Gómez‐Herrero, Julio
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 21.02.2019
• Subjects: Atomic force microscopy; Batteries; chemical bonding; Density functional theory; Diamonds; Doping; Electric contacts; Electronics; Graphene; Heterostructures; Materials science; Microscopes; Pressure effects; Silicon dioxide; Substrates; Tuning; ultrahigh pressure
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201806715

Fine‐tuning of graphene effective doping is achieved by applying ultrahigh pressures (>10 GPa) using atomic force microscopy (AFM) diamond tips. Specific areas in graphene flakes are irreversibly flattened against a SiO2 substrate. This work represents the first demonstration of local creation of very stable effective p‐doped graphene regions with nanometer precision, as unambiguously verified by a battery of techniques. Importantly, the doping strength depends monotonically on the applied pressure, allowing a controlled tuning of graphene electronics. Through this doping effect, ultrahigh pressure modifications include the possibility of selectively modifying graphene areas to improve their electrical contact with metal electrodes, as shown by conductive AFM. Density functional theory calculations and experimental data suggest that this pressure level induces the onset of covalent bonding between graphene and the underlying SiO2 substrate. This work opens a convenient avenue to tuning the electronics of 2D materials and van der Waals heterostructures through pressure with nanometer resolution. Ultrahigh pressures are applied with diamond atomic force microscopy tips to locally tune the electronic properties of graphene. Very stable and reproducible effective p‐doped regions in graphene on SiO2 are locally created. Density functional theory calculations and experimental data suggest this pressure level induces covalent bonding between graphene and the underlying SiO2 substrate.