P-channel thin film transistors using reduced graphene oxide

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Reduced graphene oxide (rGO) is a promising material for electronic applications.
• Understanding the electronic properties of rGO is crucial for device optimization.

Purpose of the Study:

• To investigate the origin of the bandgap in chemically reduced graphene oxide.
• To characterize the electronic properties of rGO for thin-film transistor applications.

Main Methods:

• Preparation of rGO with varying reduction degrees using hydrazine hydrate.
• Scanning tunneling microscopy (STM) for structural analysis.
• Scanning tunneling spectroscopy (STS) for electronic property mapping.
• Fabrication and characterization of rGO-based thin-film transistors (TFTs).

Main Results:

• STM revealed randomly distributed epoxy groups in rGO.
• STS indicated that epoxide regions are the source of the bandgap in rGO.
• Epoxide regions showed a shifted Fermi level, resulting in locally p-type behavior and bandgaps of 0-2.2 eV.
• rGO TFTs demonstrated excellent output characteristics with clear saturation and gate dependence.
• TFTs exhibited p-type semiconductor behavior with an on/off ratio of 10^4 and a hole mobility of 3.9 cm^2 V^-1 s^-1.

Conclusions:

• Epoxy groups in rGO are responsible for its semiconducting properties and tunable bandgap.
• Chemically reduced graphene oxide is a viable p-type semiconductor for high-performance thin-film transistors.