Preservation of surface conductivity and dielectric loss tangent in large-scale, encapsulated epitaxial graphene measured by non-contact microwave cavity perturbations

Published: May 19, 2017

Author(s)

Albert F. Rigosi, Nicholas R. Glavin, Chieh-I Liu, Yanfei Yang, Jan Obrzut, Heather M. Hill, Jiuning Hu, Hsin Y. Lee, Angela R. Hight Walker, Curt A. Richter, Randolph E. Elmquist, David B. Newell

Abstract

Regarding the improvement of current quantized Hall resistance (QHR) standards, one promising avenue is the growth of homogeneous monolayer epitaxial graphene (EG). A clean and simple process was used to produce large, precise areas of EG. Properties like the surface conductivity and dielectric loss tangent remain unstable when EG is exposed to air due to doping from molecular adsorption. Experimental results are reported on the extraction of the surface conductivity and dielectric loss tangent from data taken with a non-contact resonance microwave cavity, assembled with an air-filled, standard R100 rectangular waveguide configuration. By using amorphous boron nitride (a-BN) as an encapsulation layer, stability of EG’s electrical properties under ambient laboratory conditions is greatly improved. Moreover, samples were exposed to a variety of environmental and chemical conditions. Both thicknesses of a-BN encapsulation thickness are sufficient to preserve surface conductivity and dielectric loss tangent to within 10 % of its previously-measured value, a result which has essential importance in the mass production of millimeter-scale graphene devices demonstrating electrical stability.
Citation: Small
Volume: 13
Issue: 26
Pub Type: Journals

Keywords

epitaxial graphene, surface conductivity, microwave cavity, amorphous Boron Nitride (a-BN)
Created May 19, 2017, Updated November 10, 2018