A study on the solution-processed oxide semiconductors and hybrid materials for high-performance device applications

Abstract

Electronic devices became a part of human life. Future electronic devices require several things such as high performance, low-cost, fast fabrication and flexibility. The improvements of solution-based transistor and memory can satisfy these demands. In this research, we reported solution-based indium gallium zinc oxide thin film transistors (IGZO TFTs) with high performance and flexible resistive switching memory (ReRAM) using organic-inorganic hybrid perovskite. In Chapter 1, We report that patterning of indium gallium zinc oxide (IGZO) thin film transistors (TFTs) via surface modified polydimethylsiloxane (PDMS) stamping and IGZO solution for simple, low-cost, and high-speed fabrication. PDMS elastomer is prepared by immersing in piranha solution and UV ozone treatment to make hydrophilic surface. Patterned PDMS is attached to the spin coated-IGZO and transferred IGZO solution to the desired substrate. The stamped amorphous-IGZO TFTs show low leakage current, low threshold voltage, and narrow hysteresis due to no etching damage. They also show high effective mobility after annealing at 350 oC. In Chapter 2, we reported flexible oragnic-inorganic hybrid perovskite resistive switching memory. Active research has been done on hybrid organic-inorganic perovskite materials for application to solar cells with high power conversion efficiency. However, this material often shows the hysteresis which is undesirable shifts in current-voltage curve. The hysteresis may come from formation of defects and their movement in perovskite materials. Here, we utilize the defects in perovskite materials to be used in memory operations. We demonstrate flexible nonvolatile memory devices based on hybrid organic-inorganic perovskite as the resistive switching layer on plastic substrate. Uniform perovskite layer is formed on transparent electrode-coated plastic substrate by solvent engineering. The flexible nonvolatile memory based on perovskite layer shows reproducible and reliable memory characteristics in terms of program/erase operations, data retention, and endurance properties. The memory devices also shows good mechanical flexibility. It is suggested that resistive switching is done by migration of vacancy defects and formation of conducting filament under the electric field in perovskite layer. It is believed that organic-inorganic perovskite materials have a great potential to be used in high-performance, flexible memory devices.