Improving Graphene Diffusion Barriers via Stacking Multiple Layers and Grain Size Engineering

Abstract

It is shown that the performance of graphene diffusion barriers can be enhanced by stacking multiple layers of graphene and increasing grain size. The focus is on large‐area barriers of graphene grown by chemical vapor deposition (CVD) in the context of passivating an underlying Cu substrate from oxidation in air at 200 °C and use imaging Raman spectroscopy as a tool to temporally and spatially map the barrier performance and to guide barrier design. At 200 °C in air, Cu oxidation proceeds in multiple regimes: first slowly via transport through atomic‐scale grain boundary defects inherent to CVD‐graphene and then more rapidly as the graphene itself degrades and new defects are formed. In the initial regime, the graphene passivates better than previously reported. Whereas oxidation through single sheets primarily occurs through grain boundaries, oxidation through multiple sheets is spatially confined to their intersection. Performance further increases with grain‐size. The degradation of the graphene itself at 200 °C ultimately limits high temperature but suggests superior low temperature barrier performance. This study is expected to improve the understanding of mass transport through CVD‐graphene materials and lead to improved large area graphene materials for barrier applications.

Gas barrier properties of polymer/clay nanocomposites

“…16,35,40 The frequently used strategies to improve barrier properties are the use of PNCs, polymer blends, coating with high barrier materials and multilayer lms containing a high barrier lm. 25,38,42,[46][47][48] Nevertheless, it is an extremely challenging task to achieve good dispersion as well as regular arrangement of the nanoplatelets within polymer matrix. 3 Nevertheless, there is still a signicant push in the polymer industry to generate PNC lms with improved gas barrier properties.…”

Probing inhomogeneous doping in overlapped graphene grain boundaries by Raman spectroscopy

“…Moreover, GBs in graphene are known to be high-reactivity sites [11], and have been observed to induce a higher degree of oxidation of the underlying copper substrates [12][13][14]. As a result, much effort has been directed towards the growth of large area graphene films by the suppression of nucleation sites [4,[15][16][17][18].…”

Improvement of Conductivity in Graphene by Ag Nanowires under a Non-Uniform Electric Field

“…Since the graphene is an excellent diffusion barrier at elevated temperatures, the stability of AgNWs can be improved by the deposition of graphene. 25,26 After thermal annealing, the R sh of hybrids 2 and 3 decreased to 847 and 891 /sq., respectively, which indicates 20% and 16% decreases in the R sh compared to that of hybrid 1 (non-annealed), respectively. Significant differences between hybrids 2 and 3 were not observed, implying that the thermal annealing step had more influence on the electrical properties of the AgNWs than on those of graphene.…”