Fragmented graphene synthesized on a dielectric substrate for THz applications

Hamza Rehman; Lena Golubewa; Alexey Basharin; Andzej Urbanovic; Erkki Lahderanta; Ekaterina Soboleva; Ieva Matulaitiene; Marija Jankunec; Yuri Svirko; Polina Kuzhir

doi:10.1088/1361-6528/ac7403

Fragmented graphene synthesized on a dielectric substrate for THz applications

Nanotechnology. 2022 Jul 7;33(39). doi: 10.1088/1361-6528/ac7403.

Affiliations

¹ Department of Physics and Mathematics, Institute of Photonics, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland.
² Center for Physical Sciences and Technology, Saulėtekio av. 3, LT-10257 Vilnius, Lithuania.
³ Lappeenranta-Lahti University of Technology LUT, Yliopistonkatu 34, 53850, Lappeenranta, Finland.
⁴ Institute of Biochemistry, Life Sciences Center, Vilnius University, Saulėtekio al. 7, LT-10257, Vilnius, Lithuania.

PMID: 35623324
DOI: 10.1088/1361-6528/ac7403

Abstract

Fragmented multi-layered graphene films were directly synthesized via chemical vapor deposition (CVD) on dielectric substrates with a pre-deposited copper catalyst. We demonstrate that the thickness of the sacrificial copper film, process temperature, and growth time essentially influence the integrity, quality, and disorder of the synthesized graphene. Atomic force microscopy and Kelvin probe force microscopy measurements revealed the presence of nano-agglomerates and charge puddles. The potential gradients measured over the sample surface confirmed that the deposited graphene film possessed a multilayered structure, which was modelled as an ensemble of randomly oriented conductive prolate ellipsoids. THz time domain spectroscopy measurements gave theacconductivity of the graphene flakes and homogenized graphitic films as being around 1200 S cm^-1and 1000 S cm^-1, respectively. Our approach offers a scalable fabrication of graphene structures composed of graphene flakes, which have effective conductivity sufficient for a wide variety of THz applications.

Keywords: Terahertz; chemical potential; chemical vapor deposition; direct deposition; effective conductivity; graphene islands; kelvin probe force microscopy.