The electrical properties of plasma-deposited thin films derived from Pelargonium graveolens

Inherently volatile at atmospheric pressure and room temperature, plant-derived precursors present an interesting human-health-friendly precursor for the chemical vapour deposition of thin films. The electrical properties of films derived from Pelargonium graveolens (geranium) were investigated in metal-insulator-metal (MIM) structures. Thin polymer-like films were deposited using plasma-enhanced synthesis under various plasma input power. The J-V characteristics of thus-fabricated MIM were then studied in order to determine the direct current (DC) conduction mechanism of the plasma polymer layers. It was found that the capacitance of the plasma-deposited films decreases at low frequencies (C ≈ 10^-11) and remains at a relatively constant value (C ≈ 10^-10) at high frequencies. These films also have a low dielectric constant across a wide range of frequencies that decreases as the input RF power increases. The conductivity was determined to be around 10-16-10-17 Ω^-1 m^-1, which is typical for insulating materials. The Richardson-Schottky mechanism might dominate charge transport in the higher field region for geranium thin films.