Improvement of Device Characteristic on Solution-Processed InGaZnO Thin-Film-Transistor (TFTs) using Microwave Irradiation

Abstract

Abstract-Solution-derivedamorphous indiumgallium-zinc oxide (a-IGZO) thin-film-transistor (TFTs) were developed using a microwave irradiation treatment at low process temperature below 300°C. Compared to conventional furnace-annealing, the a-IGZO TFTs annealed by microwave irradiation exhibited better electrical characteristics in terms of field effect mobility, SS, and on/off current ratio, although the annealing temperature of microwave irradiation is much lower than that of furnace annealing. The microwave irradiated TFTs showed a smaller V th shift under the positive gate bias stress (PGBS) and negative gate bias stress (NGBS) tests owing to a lower ratio of oxygen vacancies, surface absorbed oxygen molecules, and reduced interface trapping in a-IGZO. Therefore, microwave irradiation is very promising to low-temperature process.

Review of flexible and transparent thin-film transistors based on zinc oxide and related materials

“…The advent of flexible transparent electronics has also boosted the development of solution process techniques, especially roll-to-roll printing and other printing technics. [19,21,115,162,181] The inks used in printing techniques will need to dissolve the zinc precursors into solvents, such as dissolving zinc hydroxide (Zn(OH) 2 ) into aqueous ammonia (NH 4 OH), [37,49] zinc acetate dihydrate [Zn(CH 3 COO) 2 ] into 2-methoxyethanol (CH 3 OCH 2 CH 2 OH) [28,46,93,95,[197][198][199][200] and zinc chloride (ZnCl 2 ) into ethylene glycol (C 2 H 6 O 2 ). [62] Thus, a high-temperature (> 300 • C) post-annealing is essential to fully decompose the organic components and produce a pure-phase metal oxide from the solution phase, which is not compatible with most of the flexible substrates.…”

Continuous-Wave Green Laser Activation of Transparent InZnO Electrodes for Fully Solution-Processed Oxide Thin-Film Transistors

“…The most common strategy is performing a thermal annealing step > 400 °C for several hours to achieve acceptable device performance. 10,14,15 Attempts to lower the induced temperature on the device involve the use of microwave annealing, 16,17 high-pressure annealing, 18,19 and photochemical activation. 20−23 In particular, photoactivation is a sustainable technique wherein the energetic photons from the light source aid in the decomposition of precursors and the subsequent densification of metal oxide.…”

“…Since films formed by atmospheric solution processing generally possess low quality, several postdeposition treatments are being employed. The most common strategy is performing a thermal annealing step > 400 °C for several hours to achieve acceptable device performance. ,, Attempts to lower the induced temperature on the device involve the use of microwave annealing, , high-pressure annealing, , and photochemical activation. − In particular, photoactivation is a sustainable technique wherein the energetic photons from the light source aid in the decomposition of precursors and the subsequent densification of metal oxide. , Several reports have demonstrated UV irradiation to be effective in accelerating precursor decomposition and subsequent metal-oxide formation. , On the other hand, laser irradiation is another strategy that is preferred over conventional thermal treatment in terms of addressing issues such as high thermal budget, long processing times, and incompatibility with heat-sensitive substrates, which leads to mechanical failure . Laser processing primarily works by generating high energy in a confined area using a focused laser to induce photothermal effects at a target location. − This localization of the thermal effect makes it possible to produce minimal to zero interactions with the underlying layers, substrate, or even adjacent structures, making it interesting in diverse materials processing, which requires selective annealing, − patterning, − crystal growth, , and ablation. , Laser irradiation has been used to tailor the characteristics of metal oxide films and nanostructures for diverse applications such as dielectric materials, , solar cells, ferroelectric oxide thin films, transparent conductors, ,− and TFTs. ,,,,− Previously, we demonstrated the use of excimer laser and UV irradiation to induce structural modification in an a-IZO film .…”