On the Anomalous Peak in the Forward Bias Capacitance and Dielectric Properties of the Al/Co-Doped (PVC plus TCNQ)/p-Si structures as Function of Temperature

The temperature and voltage dependence of electric and dielectric characteristics and ac electrical conductivity (sigma(ac)) of Al/Co-doped (PVC + TCNQ)/p-Si structure in the temperature range of 200-360 K and voltage range of (-4 V)-(9 V) have been investigated in detail by using experimental C-V and G/omega -V measurements at 500 kHz. The value of dielectric constant (epsilon'), dielectric loss (epsilon ''), dielectric loss tangent (tan delta), the real and imaginary parts of electric modulus (M' and M ''), and the sigma(ac) were strongly dependent applied bias voltage and temperature, especially in the depletion and accumulation regions. Such a behavior in these parameters can be explained on restructuring and reordering of charges at interface traps/states. The forward C-V plots exhibit an anomalous peak for each temperature and the peak position shift towards lower voltages with increasing temperature due to the particular density distribution of interface traps (D-it) and series resistance (Rs) of structure. Therefore the plots of dielectric properties and also sigma(ac) indicate two different behaviors before and after intersection point. Before this intersection point, while the values of the epsilon', epsilon '', and sigma(ac) increase, the tan delta decreases, after this intersection point, while the value of the epsilon', epsilon '', and sigma(ac) decrease, the tan delta increases. The ln (sigma(ac))-q/kT plot shows two linear regions both for the 2 V and 9 V which are corresponding to below room temperature (200-300 K) and above room temperature (320-360 K) and the corresponding activation energy (E-a) values were called as Ea((I)) and Ea((II)), respectively. Thus the E-a values were obtained from the slope of these Arrhenius plot as 182 meV and 4.7 meV for 2 V and 22 meV and 0.6 meV for 9 V, respectively.