Displacement current measurement of a pentacene metal–insulator–semiconductor device to investigate both quasi-static and dynamic carrier behavior using a combined waveform

Displacement current measurements (DCMs) were used to investigate transient carrier behavior during the carrier accumulation process in pentacene (Pn) metal–insulator–semiconductor structures [Au/Pn (100 nm)/SiO2 (100 nm)/p-type Si]. We propose a modified DCM technique that applies a combined voltage waveform of ramp and plateau parts to observe the transient carrier behavior. This allows to simultaneously detect both the effective capacitance of the device and the transient response which reflects the dynamic carrier behavior in the device. In addition, the long decay time during carrier spreading at the Pn/SiO2 interface agrees well with the inverse of the relaxation frequency, which was estimated by capacitance–frequency measurement. This result demonstrates that DCM is a powerful tool for investigating both the quasi-static and dynamic behavior of carriers in organic devices.

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► Carrier motion in organic MIS device is examined by displacement current measurement.
► The effective capacitance and its time dependence are observed simultaneously.
► Transient current flows while carriers are spreading at the pentacene/SiO2 interface.
► Decay time of the current corresponds with relaxation time in impedance spectroscopy.
► Displacement current measurement is a powerful tool to investigate carrier behavior.