Temperature Dependence of Raman-Active In-Plane E_2g Phonons in Layered Graphene and h-BN Flakes

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Graphene and hexagonal boron nitride (h-BN) are 2D materials with exceptional thermal conductivity.
• Understanding their thermal properties is crucial for advanced thermal management applications.

Purpose of the Study:

• To investigate and compare the temperature-dependent thermal properties of graphene and h-BN flakes.
• To analyze the behavior of in-plane E2g optical phonon peaks under varying temperatures.

Main Methods:

• Micro-Raman spectroscopy was employed to measure phonon peak shifts and broadenings.
• Experiments were conducted across a temperature range from -194 °C to 200 °C.

Main Results:

• Hexagonal boron nitride (h-BN) flakes exhibited higher sensitivity to temperature-dependent frequency shifts and broadenings than graphene flakes.
• The thermal effect along the c-direction on phonon frequency was more pronounced in h-BN than in graphene.
• Phonon broadening showed similar temperature sensitivity in both h-BN and graphene.

Conclusions:

• The study reveals distinct thermal responses of h-BN and graphene to temperature variations.
• These findings provide valuable insights into the thermal mechanisms of these 2D materials for thermal device applications.