Electrical Permittivity and Conductivity of a Graphene Nanoplatelet Contact in the Microwave Range.

Stefano Bellucci,Fulvio Schettino,Antonio Maffucci,Federico Micciulla,Daniele Pinchera,Alesia Paddubskaya,Marco Migliore,Sergey Maksimenko

doi:10.3390/ma11122519

Abstract

This paper investigates the electrical properties in the microwave range of a contact made by graphene nanoplatelets. The final goal is that of estimating the range of values for the equivalent electrical complex permittivity of a contact obtained by integrating low-cost graphene in the form of nanoplatelets (GNPs) into a high-frequency electrical circuit. To this end, a microstrip-like circuit is designed and realized, where the graphene nanoplatelets are self-assembled into a gap between two copper electrodes. An experimental characterization is carried out, both to study the structural properties of the nanomaterials and of the realized devices, and to measure the electromagnetic scattering parameters in the microwave range by means of a microstrip technique. A full-wave electromagnetic model is also derived and used to investigate the relationship between the measured quantities and the physical and geometrical parameters. The combined use of the experimental and simulation results allows for retrieving the values of the equivalent complex permittivity. The equivalent electrical conductivity values are found to be well below the values expected for isolated graphene nanoplatelets. The real part of the electrical relative permittivity attains values comparable to those obtained with GNP nanocomposites.

Highlights

In recent decades, the use of nanostructured materials in electronics has been widely investigated, given their exciting features and outstanding properties, potentially suitable to solve many of the open problems for the generations of electronics technologies [1]
The considered nanomaterial is a powder of commercial graphene nanoplatelets (GNPs), that has been characterized through analytical scanning electron microscopy, performed by means of the SEM
The mean composition identified by the SEM/EDX analysis highlights a non-negligible presence of oxygen and of impurities, such as Ca, S, Si, Al and other elements, which is the typical case for a commercial low-cost graphene material

Summary

Introduction

The use of nanostructured materials in electronics has been widely investigated, given their exciting features and outstanding properties, potentially suitable to solve many of the open problems for the generations of electronics technologies [1]. The use of carbon-based nanomaterials in electronics has been investigated for decades [4,5,6,7,8], and the proposed applications may be divided in two main categories: (i) nano-carbon as reinforcing material to realize novel composites. Materials 2018, 11, 2519; doi:10.3390/ma11122519 www.mdpi.com/journal/materials (nanocomposites); (ii) nano-carbon as alternative material to replace conductors or dielectrics in electronic devices. The use of carbon materials to replace conductors or dielectrics in electronic devices has not reached the same technology maturity. The main reasons why this technology has not yet reached the commercial stage are related to the cost of the fabrication of nanomaterials with the required quality and of their integration. The integration can be only made by means of cumbersome and expensive transfer techniques

Methods

Results

Conclusion