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 InOx 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. © 2023 The Royal Society of Chemistry.