The realization of next-generation flexible electronics involves the successful integration of functional solutionprocessed materials using simple and low-temperature fabrication techniques that are applicable to heat-sensitive substrates. Although there are numerous studies on the single solutionprocessed layer in an oxide thin-film transistor (TFT) structure, integrating all solution-based layers remains challenging. Here, fully solution-processed amorphous InZnO (a-IZO) TFTs were demonstrated utilizing the solution-based channel, gate insulator, and electrodes with a maximum fabrication temperature of 300 °C. Particularly, a single layer of a-IZO was used as both the channel and the source/drain electrode layer by selectively tuning the role of a-IZO as a semiconductor or a conductor through photoassisted treatments. By employing a self-aligned TFT structure, the a-IZO electrodes were functionalized by UV irradiation and excimer laser annealing (ELA). The fully solution-processed a-IZO TFTs exhibited high performance with an average mobility of up to 38 cm 2 V −1 s −1 , which surpasses those of previously reported approaches for fully solution-processed oxide TFTs. Moreover, the overall device performance, including a subthreshold swing of 225 mV dec −1 and an on-voltage of −0.4 V, is comparable to those of vacuum-processed oxide TFTs. In-depth analyses suggest that the successful functionalization of the a-IZO semiconductor into conductive electrodes is due to oxygen vacancy generation after UV treatment and subsequent crystallization and densification of the irradiated a-IZO areas after ELA. The demonstration of simple low-temperature photofunctionalization of solution-based oxide materials can be applied to 3D printing and can advance the high-throughput display manufacturing such as roll-to-roll processing.

Abstract. Future electronics devices are not only smaller and thinner, but are also flexible, bendable and even wearable. This evolution in technology requires direct printing of patterns onto any substrate using conductive inks made of a dispersion of metallic nanoparticles. In this study, Cl-ions was used to induce spontaneous sintering of silver nanoparticles (Ag NPs). Ag NPs with an average diameter of 56 nm were synthesized by polyol method using silver nitrate (AgNO3) and ethylene glycol (EG) as precursor and solvent, respectively. Poly(vinyl pyrrolidone) was used as the capping agent. Water-based inks were formulated containing different Ag NP loading (10-25 wt %). Using 50 mM NaCl aqueous solution as the dispersing medium, an ink with 15 wt % Ag exhibited a sheet resistance of about 2.85 Ω/sq. This very low sheet resistance was attributed to sintering of Ag NPs, which was accompanied by an increase in average diameter of nanoparticles from 56 to 569 nm.

Atomic layer deposition (ALD) of Al2O3 using dimethylaluminum hydride (DMAH) was demonstrated as an effective passivation for amorphous InGaZnO thin-film transistors (TFTs). Compared with the most commonly used precursor, trimethylaluminum, TFTs fabricated with DMAH showed improved stability, resulting from the lower amount of oxygen vacancies, and hence fewer trap sites, as shown by X-ray photoelectron spectroscopy (XPS) depth profiling analysis. We found that prolonged plasma exposure during ALD can eliminate the hump phenomenon, which is only present for DMAH. The higher Al2O3 deposition rate when using DMAH is in line with the requirements of emerging techniques, such as spatial ALD, for improving fabrication throughput.

We report the development of high performance all‐solution processed oxide thin‐film transistors (TFT) via selective photo‐induced semiconductor‐to‐conductor transformation of a‐InZnO. This simple method enables TFT fabrication through deposition of three main layers without additional source, drain, and gate deposition. This method has a large potential for high throughput roll‐to‐roll fabrication.

Highly reliable amorphous InGaZnO (a-IGZO) (In:Ga:Zn:O  =  2:2:1:7) thin-film transistors (TFTs) were fabricated with 25 nm-thick Al2O3 passivation deposited by atomic layer deposition (ALD) using dimethylaluminum hydride (DMAH). Al2O3 passivation deposited at various temperatures was studied to determine its effect on TFT behavior following gate bias stress and humidity exposure. The Al2O3-passivated a-IGZO TFTs demonstrated an on-off current ratio (Ion/Ioff) of ~108 and linear mobility (µ) of 9 to 13 cm2 V−1 s−1. An optimum ALD temperature of 200 °C was demonstrated to result in Al2O3-passivated a-IGZO TFTs with very small on-voltage shifts of 0.3 V and  −2.7 V against positive bias stress and negative bias illumination stress (NBIS) after 10 000 s of stress time. Furthermore, negligible degradation was observed after humidity exposure. The results of x-ray photoelectron spectroscopic analysis of the O 1s spectra showed the highest peak area ratio for metal–oxygen (M–O) bonding and lowest metal–oxygen vacancy (M–Vo) bonding, relating to the least amount of trap sites both in the bulk region of a-IGZO and near the interface of Al2O3/a-IGZO, for the device passivated at 200 °C. It was also found that at a low deposition temperature (⩽100 °C), low-density Al2O3 was formed with high carbon contamination and hydrogen while at a high deposition temperature (⩾300 °C), high hydrogen concentration was also present in high-density Al2O3. The hydrogen incorporation from Al2O3 passivation to a-IGZO channel creates bulk defects and trap sites as well as in the interface of a-IGZO and SiO2 gate insulator. At 200 °C, high quality Al2O3 passivation was achieved with high density and reduced impurities leading to improved device reliability. These results can be applied to long term sustained device operations which are reliable against different stresses.