Impact of C ion irradiation of pentacene organic film

Carbon ion irradiation effect on the chemical and electrical properties of pentacene organic film on Si substrate is investigated by means of Fourier transformation infrared spectrometry (FTIR) and van der Pauw method. In this study, pentacene film is grown by vacuum evaporation method. The thickness of film is 200 nm. The grown pentacene films are irradiated by carbon ions with the energy of 1.0 MeV at the dose range from 1x1012 to 1x1015/cm2 at room temperature. The influence of carbon ion irradiation on chemical properties is monitored with signals of aromatic ring related vibrations of out-of-plane C-H bending at 732 and 907 cm-1 observed in FTIR spectrum. The signal C-H bending is obviously observed up to the carbon dose of 1x1013/cm2 with the small decrease in intensity. As-deposited pentacene film shows high sheet resistance after air exposure. However, the samples after ion irradiation show sheet resistance as low as 150 Ω/sq. at in dose of 1x1012/cm2. In addition, the sheet resistance tends to increase with increasing ion dose. (author)