A comparative study of plasma polymerized organic thin films on their electrical and optical properties

Plasma polymerized organic thin films were deposited on Si(1 0 0) and glass substrates by plasma enhanced chemical vapor deposition (PECVD) method using single molecular precursors. Cyclohexane, methylcyclohexane, and ethylcyclohexene were utilized as organic precursors, and hydrogen and Ar was used as a carrier gases, respectively. To compare the difference of the electrical and the optical properties of both the plasma polymerized pure organic thin films, we grew those films under the conditions of various radio frequencies (RF using 13.56 MHz) powers in the range of 20-50 W and deposition temperatures (25 and 100 °C). The composition changes and the electrical characteristics of as-grown thin films were analyzed with I-V and C-V techniques. The optical properties of the polymerized thin films were investigated by Fourier transformed infrared spectroscopy (FT-IR) and UV-vis spectrophotometer. As the plasma power was increased, the main IR absorption peak intensity of thin films was increased while the transmittance of the UV-vis spectra was decreased, indicating high cross-linked density. Based on I-V and C-V curves of the electrical property measurement, the best leakage current density of the ethylcyclohexane thin films obtained to be around 4.5 × 10^-12 A/cm² at 1 MV/cm.