Charge Carrier Transport and Localized States in Graphite-like Amorphous Carbon Films at Room Temperatures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Electrical Engineering

Background:

• Graphite-like amorphous carbon films exhibit unique electrical properties.
• Understanding their conductivity is crucial for electronic applications.
• Annealing is a key process to modify film characteristics.

Purpose of the Study:

• To investigate the direct and alternating current conductivity of graphite-like amorphous carbon films.
• To analyze the influence of annealing at 700°C on film conductivity.
• To elucidate the underlying electrical transport mechanisms.

Main Methods:

• Studied current-voltage (I-V) characteristics.
• Analyzed frequency-dependent capacitance.
• Performed temperature-dependent resistance measurements.

Main Results:

• Symmetrical I-V characteristics with two linear sections in logarithmic coordinates.
• Observed a sharp increase in capacitance at low frequencies (Maxwell-Wagner polarization) and a decrease at high frequencies.
• Identified electron conduction with variable jump length at room temperature and an additional hopping transport mechanism with increased injection current.

Conclusions:

• The films exhibit inhomogeneous dielectric properties with conducting inclusions.
• Conduction is governed by variable-range hopping near the Fermi level at low currents.
• An additional hopping mechanism contributes to increased conductivity under higher injection currents.