Large-scale Graphitic Thin Films Synthesized on Ni and Transferred to Insulators: Structural and Electronic Properties

TL;DR

This study demonstrates the synthesis, transfer, and characterization of large-scale graphitic thin films on insulators, revealing their structural features and promising electronic properties for device applications.

Contribution

It provides a comprehensive analysis of the structural and electronic properties of large-area CVD-grown graphitic films transferred onto insulators, highlighting their potential for electronic devices.

Findings

Films contain both graphite and few-layer graphene regions.

Transferrable films exhibit ambipolar field effect with ~50% resistance modulation.

Carrier mobilities reach approximately 2000 cm²/Vs and show quantum transport phenomena.

Abstract

We present a comprehensive study of the structural and electronic properties of ultrathin films containing graphene layers synthesized by chemical vapor deposition (CVD) based surface segregation on polycrystalline Ni foils then transferred onto insulating SiO2/Si substrates. Films of size up to several mm's have been synthesized. Structural characterizations by atomic force microscopy (AFM), scanning tunneling microscopy (STM), cross-sectional transmission electron microscopy (XTEM) and Raman spectroscopy confirm that such large scale graphitic thin films (GTF) contain both thick graphite regions and thin regions of few layer graphene. The films also contain many wrinkles, with sharply-bent tips and dislocations revealed by XTEM, yielding insights on the growth and buckling processes of the GTF. Measurements on mm-scale back-gated transistor devices fabricated from the transferred GTF show ambipolar field effect with resistance modulation ~50% and carrier mobilities reaching ~2000 cm^2/Vs. We also demonstrate quantum transport of carriers with phase coherence length over 0.2 $\mu$m from the observation of 2D weak localization in low temperature magneto-transport measurements. Our results show that despite the non-uniformity and surface roughness, such large-scale, flexible thin films can have electronic properties promising for device applications.