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Published on: July 24, 2015
Tuning the work function of monolayer graphene on 4H-SiC (0001) with nitric acid
Fethullah Günes1, Hakim Arezki, Debora Pierucci
1GeePs, CNRS UMR8507, CentraleSupelec, Univ Paris-Sud, Sorbonne Universités-UPMC Univ Paris 06, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette Cedex, France. Department of Materials Science and Engineering, Izmir Kâtip Çelebi University Cigli Main Campus, 35620, IZMIR, Turkey.
Abstract:
Chemical doping of graphene is a key process for the modulation of its electronic properties and the design and fabrication of graphene-based nanoelectronic devices. Here, we study the adsorption of diluted concentrations of nitric acid (HNO3) onto monolayer graphene/4H-SiC (0001) to induce a variation of the graphene work function (WF). Raman spectroscopy indicates an increase in the defect density subsequent to the doping. Moreover, ultraviolet photoemission spectroscopy (UPS) was utilized to quantify the WF shift. UPS data show that the WF of the graphene layer decreased from 4.3 eV (pristine) down to 3.8 eV (30% HNO3) and then increased to 4.4 eV at 100% HNO3 concentration. These observations were confirmed using density functional theory (DFT) calculations. This straightforward process allows a large WF modulation, rendering the molecularly modified graphene/4H-SiC(0001) a highly suitable electron or hole injection electrode.
