High-performance oxide thin-film diode and its conduction mechanism based on ALD-assisted interface engineering

Abstract

Rectifying diodes have emerged as one of the promising components for advanced functional devices, including resistive random access memory and backplanes of active-matrix systems. Among various types of diodes, oxide thin film diodes have been extensively studied for their outstanding stability and rectifying characteristics. In this study, we developed a metal–oxide semiconductor–insulator–metal (MSIM) diode by atomic layer deposition-assisted interface engineering and obtained a high on–off ratio of ∼10⁸, low off-current density of 10⁻⁹ A cm⁻² and good reliability. For the first time, the operation mechanism of the MSIM diode was also scrutinized with chemical analyses. X-Ray photoelectron spectroscopy and density functional theory results indicate that trimethylaluminum induced oxygen vacancies at the interface between InO_x and Al₂O₃ through a reduction reaction during Al₂O₃ deposition. The induced oxygen vacancies promote the formation of abundant tail states near the interface, and the tail states contribute to the injection of electrons from the cathode into Al₂O₃. From chemical and electrical analyses, suitable conduction mechanism and energy band diagram of the MSIM diode were proposed in detail. Consequently, the MSIM diode has been successfully demonstrated on a flexible polyimide substrate without degradation of rectifying characteristics, providing the potential of the MSIM diode as an advanced electronic device.