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

摘要

The energy dependence of the interface states $(N_{{rm ss}})$ and relaxation time $(tau)$ and capture cross section $(sigma_{{rm p}})$ of $N_{{rm ss}}$ in $({rm Au}/{rm PVC}+{rm TCNQ}/{rm p}hbox{-}{rm Si})$ heterojunction were investigated using high–low frequency capacitance $(C_{{rm HF}}-C_{{rm LF}})$ and conductance method, which contains many capacitance/conductance $[C/(G/omega)-V]$ plots. The $C$ value of the heterojunction increases with decreasing frequency as almost exponentially due to the existence of $N_{{rm ss}}$ between metal and semiconductor. The $N_{{rm ss}}$ and $tau$ values have been obtained in the (0.053-$E_{{rm v}}$)-(0.785- $E_{{rm v}}$)-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 $N_{{rm ss}}$ ranges from $3.88times 10^{12}~{rm eV}^{-1}{rm cm}^{-2}$ to $3.24times 10^{{12}}~{rm eV}^{-1}{rm cm}^{-2}$. In the same energy range, the value of $tau$ ranges from $5.73times 10^{-5}$ to $1.58times 10^{-4}~{rm s}$ and shows almost an exponential increase with increasing bias from the top of the valance band edge toward the midgap of semiconductor. The obtained $N_{{rm ss}}$ values from $C_{{rm HF}}{-}C_{{rm LF}}$ and conductance methods are in good agreement with each other for the heterojunction. As a result, the mean value of $N_{{rm ss}}$ was found on the order of $10^{12}~{rm eV}^{-1}{rm cm}^{-2}$ and this value is very suitable for an electronic device.