Following the Long-Term Evolution of sp${}^3$-type Defects in Tritiated Graphene using Raman Spectroscopy

Abstract

We report on the evolution of tritium-induced sp${}^3$-defects in monolayer graphene on a Si/SiO${}_2$ substrate, by comparing large-area Raman maps of the same two samples, acquired just after fabrication and twice thereafter, about 9-12 months apart. Inbetween measurements the samples were kept under standard laboratory conditions. Using a conservative classification of sp${}^3$-type spectra, based on the D/D' peak intensity ratio, we observed almost complete depletion of sp${}^3$-type defects over the investigation period of about two years. This by far exceeds the ~5.5% annual reduction expected from tritium decay alone (~3x larger). This change in the defect composition is accompanied by a recovery of the 2D-band of graphene and an overall decrease in defect-density, as determined via the D/G intensity ratio. Hydogenated graphene is reported to be reasonably stable over several months, when kept under vacuum, but suffers substantial hydrogen loss under laboratory air conditions. While the results shown here for tritiated graphene exhibit similarities with hydrogenated graphene, however, some distinct differences are observed.

Submitted to Nanoscale Advances

References in corpus (10)

• Electric Field Effect in Atomically Thin Carbon Films
• The electronic properties of graphene
• The Raman Fingerprint of Graphene
• Control of graphene's properties by reversible hydrogenation
• Probing the Nature of Defects in Graphene by Raman Spectroscopy
• Graphane: a two-dimensional hydrocarbon
• 4He on a single graphene sheet
• Reversible hydrogenation and band gap opening of graphene and graphite surfaces probed by scanning tunneling spectroscopy
• Demonstration of tritium adsorption on graphene
• Graphene structure modification under tritium exposure: 3H chemisorption dominates over defect formation by \b{eta}-radiation