Following the long-term evolution of sp³-type defects in tritiated graphene using Raman spectroscopy

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Monolayer graphene on Si/SiO₂ substrates is a promising material for electronic applications.
• Understanding defect evolution is crucial for device stability and performance.
• Tritium incorporation can induce sp³-defects in graphene.

Purpose of the Study:

• To investigate the long-term evolution of tritium-induced sp³-defects in monolayer graphene.
• To compare the observed defect reduction rate with that expected from tritium decay.
• To analyze the impact of defect evolution on graphene's electronic properties.

Main Methods:

• Utilized large-area Raman spectroscopy to map defect distribution.
• Acquired Raman spectra at multiple time points over two years.
• Classified sp³-defects using the D/D' peak intensity ratio.
• Quantified overall defect density via the D/G intensity ratio.

Main Results:

• Observed near-complete depletion of sp³-defects over two years, exceeding tritium decay predictions by over three times.
• Detected a recovery of the graphene 2D-band and a decrease in overall defect density.
• Noted similarities and distinct differences compared to hydrogenated graphene stability.

Conclusions:

• Tritium-induced sp³-defects in graphene are unstable under standard laboratory conditions.
• Environmental factors significantly accelerate defect reduction beyond radioactive decay.
• Graphene's stability under ambient conditions requires further investigation, especially concerning isotopic effects.