Molecular absorption and photodesorption in pristine and functionalized large-area graphene layers

Area of Science:

• Materials Science
• Surface Science
• Nanotechnology

Background:

• Graphene's electrical properties are sensitive to surface adsorbates and environmental conditions.
• Photodesorption, the light-induced release of adsorbed molecules, can alter graphene's electronic behavior.
• Chemical Vapor Deposition (CVD) is a key method for large-area graphene fabrication.

Purpose of the Study:

• To investigate the photodesorption behavior of pristine and nitric acid (HNO(3)) treated graphene.
• To understand the impact of UV illumination on graphene's electrical conductivity and carrier mobility.
• To explore HNO(3) treatment as a strategy for stabilizing graphene's electrical performance.

Main Methods:

• Fabrication of graphene layers using Chemical Vapor Deposition (CVD).
• Treatment of graphene with concentrated nitric acid (HNO(3)).
• Characterization of electrical conductivity and Dirac point shift under ultraviolet (UV) light exposure.

Main Results:

• UV illumination causes molecular photodesorption, decreasing electrical conductivity and shifting the Dirac point in pristine graphene.
• UV illumination does not significantly degrade carrier mobility in graphene.
• HNO(3) treatment reduces the photodesorption-induced current decrease in graphene, indicating enhanced stability.
• HNO(3) functionalization likely passivates defect sites, preventing further gas molecule absorption.

Conclusions:

• Nitric acid treatment offers a viable strategy to stabilize the electrical performance of CVD-grown graphene.
• Stabilized graphene is more suitable for applications in nanoelectronics and optoelectronics.
• Understanding photodesorption is crucial for reliable graphene-based device operation.