Double-exponential current-voltage (I-V) and negative capacitance (NC) behavior of Al/(CdSe-PVA)/p-Si/Al (MPS) structure

In this study, I-V and C-V characteristics of the Al/(CdSe-PVA)/p-Si/Al (MPS) structure have been investigated the by taking into account double-exponential I-V and NC behavior. The structural characterization of CdSe nanocrystals were analyzed by X-ray diffraction(XRD), scanning electron micros-copy (SEM), and energy dispersive X-ray (EDX) techniques. These results show that the prepared CdSe consists of spherical monodispersed nanocrystalites of about 200nm; aggregated in the form of poly-dispersive nanoclusters of arbitrary shape with the size in the range of 150-300nm and they are in good agreement with those estimated from the XRD pattern. The forward bias LnI-V plot of the MPS structure has two linear parts which are called low bias Region 1 (R1:0.25-0.65V) and moderate bias Region 2 (R2:0.70-1.20V). The ideality factor (n) and barrier height (BH:phi(B0)) were found to be 9.38 and 0.61eV for R1 and 6.51 and 0.65eV for R2, respectively. The current conduction/transport mechanism (CCM/CTM) are also defined by forward I-VLn(I)-V and reverse bias In(IR)-VR1/2 plots. I-VLn(I)-V plot has also two linear parts which are also called (R1:-3.02/-0.29) and (R2:-0.10/1.60) obey I similar to V-m law. The slope (m) of them was found to be 1.63 and 4.57 which are corresponding to ohmic and trap-charge limited current (TCLC) mechanisms, respectively. Moreover, the value of phi(B(C-V)) was found from the linear part of C-2-V plot as 0.79eV which is higher than the obtained forward bias lnI-V plot due to the nature of measured method.