Impedance Spectroscopy Modeling of Solution-Processed Amorphous Indium-Gallium-Zinc-Oxide Metal-Semiconductor-Metal Diode

In this study, we analyze the impedance spectroscopic characteristics of solution-processed amorphous indium-gallium-zinc-oxide (a-IGZO) metal-semiconductor-metal diodes adopting aluminum and heavily doped Si electrodes. The Cole–Cole plots extracted from the capacitance-voltage ( C – V ) measurements exhibited variations depending on the voltage bias polarity and were simplified using two types of equivalent circuits. These circuits include the effects of oxidation near the aluminum electrode, tunneling at the metal/a-IGZO layer interface from the tunneling diode model, and the presence of native oxide. The thickness dependence of the C – V measurements indicates that oxidation of the Al electrodes and the quantum mechanical distribution of the electron density dominantly affected the C – V results at the Al/IGZO interface.