Frequency dependent dielectric properties in Schottky diodes based on rubrene organic semiconductor

Al/rubrene/p-Si Schottky diode has been fabricated by forming a rubrene layer on p type Si by using the spin coating method. The frequency and voltage dependent dielectric constant (epsilon'), dielectric loss (epsilon ''), tangent loss (tan delta), electrical modulus (M' and M ''), and ac electrical conductivity (sigma(ac)) properties of Al/rubrene/p-Si Schottky diodes have been investigated in the frequency range of 1 kHz-1 MHz at room temperature. It is found that the values of the epsilon', epsilon '' and tan delta decrease with increasing frequency while an increase is observed in sigma(ac) and the real component (M') of the electrical modulus. The values of epsilon', epsilon '', and tan delta were found as 5.01, 2.55, and 0.51 for 1 kHz and 2.46, 0.069, and 0.028 for 1 MHz at zero bias, respectively. Furthermore, the imaginary component (M '') of the electric modulus showed a peak that shifts to a higher voltage with decreasing frequency. (c) 2013 Elsevier B.V. All rights reserved.