On the frequency and voltage dependence of admittance characteristics of Al/PTCDA/P-Si (MPS) type Schottky barrier diodes (SBDs)

Abstract

The admittance measurements which are including capacitance/conductance–voltage–frequency (C–V–f and G/ω–V–f) measurements of the Al/PTCDA/p-Si (MPS) type Schottky barrier diodes (SBDs) were investigated in the frequency and voltage range of 10kHz–1MHz and (−3V) to (3V) at room temperature. C and G/ω values were found as strong functions of frequency especially in depletion and accumulation regions due to the effect of interface states (Nss) and series resistance (Rs), respectively. The main electrical parameters such as doping concentration atoms (NA), diffusion potential (Vd), Fermi energy level (EF) and barrier height (ΦB(C–V)) values were obtained from the reverse bias C−2 vs V plots for each frequency. The voltage dependent resistivity (Ri) profile was also obtained from the Ci and Gi data and they exhibit an anomalous peak in the depletion region due to particular distribution of Nss at polymer (PTCDA)/Si interface. In addition, the energy density distribution profile of Nss and their relaxation time (τ) were obtained from the measured C–f and G/ω–f characteristics for various forward bias voltages and they were ranged from 3.06×1012eV−1cm−2 to 3.29×1012eV−1cm−2 and 6.20μs to 8.41μs, respectively, in the energy range of Ev-0.479 and Ev-0.501eV, respectively. These results confirmed that the value of Nss may be passivized by PTCDA interfacial layer and such low value of Nss is very suitable for the fabrication MPS type SBDs in the electronic industry.