Investigation of the metal–semiconductor interface by equivalent circuit model in zinc phthalocyanine (ZnPc) based Schottky diodes and its charge transport properties

Abstract

In this report, the ZnPc-based metal–semiconductor (MS) junction Schottky devices (Al/ZnPc/ITO) were fabricated using an effusion cell coating unit. To study the formation of the MS junction, the surface morphology of the deposited ZnPc thin film was investigated using field-emission scanning electron microscope (FESEM) images. The interfacial properties of the MS junction of the Al/ZnPc/ITO configuration were studied using the ac impedance spectroscopy technique within the frequency range of 50 Hz–10 MHz at room temperature (300 K). The bias-dependent impedance spectroscopy was carried out within the voltage range of ±1 V to establish the equivalent circuit of the MS junction Schottky diodes (SDs). The current vs. voltage (I-V) measurements of the fabricated SDs were also conducted to deduce the diode parameters, namely on/off ratio, photosensitivity, ideality factor, barrier height, and series resistance. The charge transport parameters including dc conductivity, mobility and transit time of the charge carriers were also estimated employing the spatial-charge limited current (SCLC) theory, which illustrates the enhanced carrier’s mobility and consequently, the device performance after light irradiation.