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 200 nm; aggregated in the form of poly-dispersive nanoclusters of arbitrary shape with the size in the range of 150-300 nm 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 (R1:0.25-0.65 V) and moderate bias Region 2 (R2:0.70-1.20 V). The ideality factor (n) and barrier height (BH:Φ_B0) were found to be 9.38 and 0.61 eV for R1 and 6.51 and 0.65 eV for R2, respectively. The current conduction/transport mechanism (CCM/CTM) are also defined by forward I–VLn(I)–V and reverse bias In(IR)–VR^1/2 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 ~ 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 Φ_B(C–V) was found from the linear part of C⁻²-V plot as 0.79 eV which is higher than the obtained forward bias lnI–V plot due to the nature of measured method.