The modification of Schottky barrier height of Au/p-Si Schottky devices by perylene-diimide

Perylene-diimide (PDI) thin film was fabricated by spin coating method on p-Si single-crystal substrate to prepare Au/PDI/p-Si Schottky device. The electrical properties of the Au/PDI/p-Si Schottky device were investigated by current-voltage (I-V) measurements in the temperature range 80-300 K and room temperature capacitance-voltage (C-V) measurement. Results showed a rectification behavior. Junction parameters such as ideality factor (n), barrier height (φ B 0), series resistance (R s) interface state density (N s s), built-in potential (V b i), carrier concentration (N A), and the width of the depletion layer (W D) were obtained from the I-V and C-V measurements. The values of ideality factor (n) and barrier height (BH) for the Au/PDI/p-Si structure from the I-V measurements were obtained as 1.77 and 0.584 eV at 300 K, 7.78 and 0.176 eV at 80 K, respectively. It was seen that the BH value of 0.584 eV calculated for the Au/PDI/p-Si structure was significantly larger than the value of 0.34 eV of conventional Au/p-Si Schottky diodes at room temperature. Thus, modification of the interfacial potential barrier for Au/p-Si diodes has been achieved using a thin interlayer of the peryleen-diimide organic semiconductor; this has been ascribed to the fact that the peryleen-diimide interlayer increases the effective barrier height because of the interface dipole induced by passivation of the organic layer. Furthermore, the energy distribution of the interface state density determined from I-V characteristics increases exponentially with bias from 1.11 × 1012 eV -1 cm-2 at (0.556 - E v) eV to 11.01 × 10 13 eV-1 cm-2 at (0.449 - E v) eV. © 2013 American Institute of Physics.