Capacitance/Conductance–Voltage–Frequency Characteristics of ${\rm Au}/{\rm PVC}+{\rm TCNQ}/{\rm p}\hbox {-}{\rm Si}$ Structures in Wide Frequency Range

The energy dependence of the interface states (N_ss) and relaxation time (τ) and capture cross section (σp) of N_ss in (Au/PVC+TCNQ/p-Si) heterojunction were investigated using high-low frequency capacitance (C_HF-C_LF) and conductance method, which contains many capacitance/conductance [C/(G/ω)-V] plots. The C value of the heterojunction increases with decreasing frequency as almost exponentially due to the existence of N_ss between metal and semiconductor. The N_ss and τ values have been obtained in the (0.053- E_v)-(0.785- E_v)-eV energy range by considering the voltage-dependent surface potential obtained from the lowest measurable frequency C-V curve at 1 kHz. The magnitude of N_ss ranges from 3.88×10¹² eV^-1cm^-2 to 3.24×10¹² eV^-1cm^-2. In the same energy range, the value of τ ranges from 5.73×10^-5 to 1.58×10^-4 s and shows almost an exponential increase with increasing bias from the top of the valence band edge toward the midgap of semiconductor. The obtained N_ss values from C_HF-C_LF and conductance methods are in good agreement with each other for the heterojunction. As a result, the mean value of N_ss was found on the order of 10¹² eV^-1cm^-2 and this value is very suitable for an electronic device.