The origin of anomalous peak and negative capacitance in the forward bias capacitance-voltage characteristics of Au/PVA/n-Si structures

The frequency dependence of capacitance-voltage (C-V) and conductance-voltage (G/omega-V) characteristics of the Au/polyvinyl alcohol (Ni, Zn-doped)/n-Si Schottky barrier diodes (SBDs) was investigated in the frequency range of 3 kHz-3 MHz at room temperature by considering series resistance (R-s) and interface states (N-ss) effects. The C-V and G/omega-V characteristics confirm that the R-s and N-ss are important parameters that strongly influence the electrical parameters of SBDs. The C-V plots show an intersection point (similar to 2.9 V) at low frequencies (f <= 30 kHz) and then take negative values, which is known as negative capacitance (NC) behavior. The negativity of the C increases with the decreasing frequency in the forward bias voltage region, and this decrement in the NC corresponds to the increment in the conductance. Also, the forward bias C-V plots show an anomalous peak in the voltage range of 1.55-1.9 V depending on the frequency such that the anomalous peaks shift toward positive voltage values with the increasing frequency. The effect of R-s on the C is found appreciable at high frequencies. In addition, the values of N-ss and R-s are found to decrease with the increasing frequency. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3554479]