Issue 8, 2014

Exploring and rationalising effective n-doping of large area CVD-graphene by NH3

Abstract

Despite the large number of papers on the NH3 doping of graphene, the achievement of stable n-doped large area CVD (chemical vapor deposition) graphene, which is intrinsically p-doped, is still challenging. A control of the NH3 chemisorption and of the N-bond configuration is still needed. The feasibility of a room temperature high pressure NH3 treatment of CVD graphene to achieve n-type doping is shown here. We use and correlate data for (a) sheet resistance, Rsh, and the Hall coefficient, RH, in van der Pauw configuration, acquired in real time during the NH3 doping of CVD-graphene on a glass substrate, (b) optical measurements of the effect of doping on the graphene Van Hove singularity point at 4.6 eV in the dielectric function spectra by spectroscopic ellipsometry, and of (c) N-bond configuration by XPS to better understand and, finally, control the NH3 doping of graphene. The discussion is focused on the thermal and time stability of the n-doping after air exposure. A chemical rationale is provided for the NH3 n-doping based on the interaction of (i) NH3 with intrinsic oxygen functionalities and defects of CVD graphene and of (ii) C-NH2 doping centers with acceptor species present in the air.

Graphical abstract: Exploring and rationalising effective n-doping of large area CVD-graphene by NH3

Article information

Article type
Paper
Submitted
21 Oct 2013
Accepted
16 Dec 2013
First published
16 Dec 2013

Phys. Chem. Chem. Phys., 2014,16, 3632-3639

Exploring and rationalising effective n-doping of large area CVD-graphene by NH3

G. V. Bianco, M. Losurdo, M. M. Giangregorio, P. Capezzuto and G. Bruno, Phys. Chem. Chem. Phys., 2014, 16, 3632 DOI: 10.1039/C3CP54451F

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