Optical limiting in multilayer graphene films on a cobalt buffer-layer produced by the sputtering technique

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Graphene synthesis is crucial for advanced electronic and optical applications.
• Controlling multilayer graphene (MLG) properties requires precise fabrication techniques.
• Cobalt catalysts are explored for graphene growth via chemical vapor deposition.

Purpose of the Study:

• To develop a sputtering and annealing method for producing MLG thin films.
• To characterize the structural and optical properties of the synthesized MLG.
• To evaluate the potential of MLG films as optical limiters.

Main Methods:

• Multilayer graphene thin films were produced by sputtering on a cobalt buffer layer.
• Thermal annealing was performed post-deposition to facilitate graphene formation.
• Atomic force microscopy (AFM) and Raman spectroscopy were used for structural characterization.
• Transmission electron microscopy (TEM) corroborated Raman findings.
• Nonlinear absorption was measured using transmittance at 980 nm with a diode laser.

Main Results:

• MLG films with thicknesses of ~54 nm were successfully fabricated.
• Raman spectroscopy confirmed MLG formation with an I_2D/I_G ratio of 0.4 after annealing at 750°C for 25 min.
• AFM determined film thickness and roughness.
• Transmittance measurements revealed large nonlinear absorption properties.

Conclusions:

• The sputtering and annealing method is effective for producing MLG films.
• The synthesized MLG films possess desirable nonlinear optical properties.
• These MLG films show promise for use in optical limiter devices.