On the frequency-dependent complex-dielectric, complex-electric modulus and conductivity in Au/(NiS:PVP)/n-Si structures

摘要

The values of complex-dielectric (ε* =ε'- jε''), loss-tangent (tanδ), complex-electric modulus (M* = M' + jM''), and ac electrical-conductivity (σ_(ac)) of the performed Au/(NiS:PVP)/n-Si structures were extracted from the measured impedance-spectroscopy method (ISM) in frequency range of 10 kHz-1 MHz and voltage ((- 2 V)-(+ 3 V)). These parameters, which constitute the main subject of our study, have been obtained from high frequency and voltage values, more particularly in the depletion and accumulation regions. The decrease of dielectric-constant (ε'), dielectric-loss (ε''), and tanδ with increasing frequency for almost every voltage were explained by Maxwell-Wagner type relaxation processes. The observed higher-values of ε' and ε'' at low frequencies result from surface-states (N_(ss)) and dipole-polarization. Since N_(ss) has sufficient time to keep up with the applied voltage signal, dipoles can respond to the electric field to reorient themselves. An increase in M' values was observed at increasing frequency values attributed to the long-distance mobility of the carriers. On the other hand, the observed peak in the M''- In (f) curves was attributed to a distinctive distribution of N_(ss) located at Au/(NiS:PVP) interface depend on their lifetime. The obtained value of e' even at 10 kHz at 3 V is indicated that the used (NiS:PVP) organic-interlayer can be used a superior alternative instead of SiO_2 or SnO_2 which are conventional interlayers thanks to its low-cost, flexibility, easy production techniques such as spin-coating or electro-spinning technique at room condition, successfully.