Photonic Curing of Solution-Processed Indium Zinc Oxide Thin-Film Transistors

Abstract

Abstract Body: Metal oxide semiconductors such as indium gallium zinc oxide (IGZO) and indium zinc oxide (IZO) have received significant attention over the past few decades due to their desirable electrical and optical properties. Sol-gel techniques are commonly employed to deposit these materials because of the simplicity of the synthesis and the ability to easily tune the film composition. These sol-gel based oxide semiconductors often demonstrate high field-effect mobility even in the amorphous phase, but temperatures of at least 300 C are typically required to decompose the sol-gel and form high-quality semiconductor film. The desire to create high-quality flexible transistors on low-temperature plastic substrates has driven an investigation into alternative thermal processing methods for oxide semiconductors. One such option being explored is pulsed-light processing based on flashlamps, commonly known as photonic curing. Photonic curing offers advantages over conventional thermal processing methods such as ultra-short processing time and compatibility with low-temperature substrates. However, previous work on photonically cured thin-film transistors (TFTs) often results in significant heating of the entire substrate rather than just the thin film at the surface. In this talk, we will discuss our recent work using photonic curing to rapidly and effectively convert metal oxide sol-gels to realize high-quality TFTs. Sol-gel indium zinc oxide (IZO) based TFTs are photonically cured with efficient molybdenum gate absorbers using a xenon flashlamp (NovaCentrix PulseForge 1300) using intense white light delivering radiant energy up to 6 Jcm-2. Simulations indicate that the IZO film reaches a peak temperature of ~590 C while the back of the glass substrate stays near room temperature. This process yields TFTs with a field effect mobility above 20 cm2V-1s-1 and an IOn/IOff ratio approaching 108, which exceeds the performance of samples annealed at 500 C for 1 hr. We will discuss the requirements and design guidelines for photonic curing metal oxide semiconductors for high-performance TFT applications, focusing on the importance of effective gate absorbers and optimized pulse designs to efficiently and effectively cure the sol-gel films.