Analysis of interface states and series resistance for Al/PVA:n-CdS nanocomposite metal-semiconductor and metal-insulator-semiconductor diode structures

This paper presents the fabrication and characterization of Al/PVA:n-CdS (MS) and Al/Al2O3/PVA:n-CdS (MIS) diode. The effects of interfacial insulator layer, interface states (N (ss) ) and series resistance (R (s) ) on the electrical characteristics of Al/PVA:n-CdS structures have been investigated using forward and reverse bias I-V, C-V, and G/w-V characteristics at room temperature. Al/PVA:n-CdS diode is fabricated with and without insulator Al2O3 layer to explain the effect of insulator layer on main electrical parameters. The values of the ideality factor (n), series resistance (R (s) ) and barrier height (I center dot (b) ) are calculated from ln(I) vs. V plots, by the Cheung and Norde methods. The energy density distribution profile of the interface states is obtained from the forward bias I-V data by taking into account the bias dependence ideality factor (n(V)) and effective barrier height (I center dot (e) ) for MS and MIS diode. The N (ss) values increase from mid-gap energy of CdS to the bottom of the conductance band edge for both MS and MIS diode.