Paraffin-enabled graphene transfer

Wei Sun Leong,Ahmad Zubair,Tomas Palacios,Yunwei Mao,Francisco J Martin-Martinez,Pin-Chun Shen,Haozhe Wang,Markus J Buehler,Jingjie Yeo,Jing Kong,Jin-Yong Hong

doi:10.1038/s41467-019-08813-x

Abstract

The performance and reliability of large-area graphene grown by chemical vapor deposition are often limited by the presence of wrinkles and the transfer-process-induced polymer residue. Here, we report a transfer approach using paraffin as a support layer, whose thermal properties, low chemical reactivity and non-covalent affinity to graphene enable transfer of wrinkle-reduced and clean large-area graphene. The paraffin-transferred graphene has smooth morphology and high electrical reliability with uniform sheet resistance with ~1% deviation over a centimeter-scale area. Electronic devices fabricated on such smooth graphene exhibit electrical performance approaching that of intrinsic graphene with small Dirac points and high carrier mobility (hole mobility = 14,215 cm2 V−1 s−1; electron mobility = 7438 cm2 V−1 s−1), without the need of further annealing treatment. The paraffin-enabled transfer process could open realms for the development of high-performance ubiquitous electronics based on large-area two-dimensional materials.

Highlights

The performance and reliability of large-area graphene grown by chemical vapor deposition are often limited by the presence of wrinkles and the transfer-process-induced polymer residue
chemical vapor deposition (CVD) monolayer graphene grown on Cu foil was used because graphene synthesized in this manner is the most widely used source of large-area graphene in state-of-the-art research and industrial development, despite being polycrystalline and having lower mobility values
Our paraffin-transferred graphene exhibits homogeneous and improved electrical properties as a result of reduced support layer contamination and wrinkle compared to the PMMA-transferred graphene

Summary

Introduction

The performance and reliability of large-area graphene grown by chemical vapor deposition are often limited by the presence of wrinkles and the transfer-process-induced polymer residue. Mobility values as high as 200,000 cm[2] V−1 s−1 have been reported for freely suspended graphene exfoliated from bulk crystal at 5 K2, the mobility values reported for large-area graphene is several orders of magnitude lower, regardless of the growth method or substrate employed[3,4,5,6,7]. This significant decrease in carrier mobility in large-area graphene can be attributed to four factors: (1) polycrystalline nature of graphene, (2) effect of surrounding medium, (3) contamination from transfer support layer, and (4) wrinkles present in graphene. To fabricate graphene-based functional electronics, graphene must be transferred from the growth substrate to a destination substrate

Methods

Results

Conclusion