Young-Jin Kwack

Inkjet-Printed In2O3 Thin-Film Transistor below 200 °C

High-performance In2O3 thin-film transistors could be prepared by an inkjet-printing method below 200 °C with a single precursor and solvent formulation. The self-combustion reaction took place with the electrical properties of In2O3 at a low temperature of 147 °C, which was confirmed by X-ray photoelectron spectroacopy and thermal analysis. The electrical properties after postannealing at 200 °C were as follows: a mobility of 3.98 cm(2)/V·s, a threshold voltage of 1.83 V, a subthreshold slope of 0.4 V/dec, and an on-to-off current ratio of 10(8), which are the best properties by an inkjet process thus far. The positive bias stability was much improved by postannealing, and good negative bias stability was obtained.

Electrohydrodynamic Jet Spraying Technique for Oxide Thin-Film Transistor

Electrohydrodynamic (EHD) jet is a printing technique using an electric field to create jetting droplets for the delivery of a liquid portion to a designated substrate. EHD jet spraying was applied to the preparation of a solution-processed zinc-tin-oxide thin-film transistor. The electrosprayed film was characterized by analytical methods. Electrical properties, such as a mobility of 4.89 cm²·V·s^-1, a threshold voltage of 7.17 V, a subthreshold slope of 0.44 V·dec^-1, and an on-to-off ratio of 10⁷, were obtained.

A mixed solution-processed gate dielectric for zinc-tin oxide thin-film transistor and its MIS capacitance

Solution-processed gate dielectrics were fabricated with the combined ZrO2 and Al2O3 (ZAO) in the form of mixed and stacked types for oxide thin film transistors (TFTs). ZAO thin films prepared with double coatings for solid gate dielectrics were characterized by analytical tools. For the first time, the capacitance of the oxide semiconductor was extracted from the capacitance-voltage properties of the zinc-tin oxide (ZTO) TFTs with the combined ZAO dielectrics by using the proposed metal-insulator-semiconductor (MIS) structure model. The capacitance evolution of the semiconductor from the TFT model structure described well the threshold voltage shift observed in the ZTO TFT with the ZAO (1:2) gate dielectric. The electrical properties of the ZTO TFT with a ZAO (1:2) gate dielectric showed low voltage driving with a field effect mobility of 37.01 cm2/Vs, a threshold voltage of 2.00 V, an on-to-off current ratio of 1.46 × 105, and a subthreshold slope of 0.10 V/dec.

Solution-processed zinc-tin-oxide thin-film transistor by electrohydrodynamic spray

Solution-processed zinc-tin-oxide film was coated by electrohydrodynamic (EHD) jet. By using EHD spray technique, zinc-tin-oxide (ZTO) TFT was prepared and characterized for the first time. The optimized process parameters were as follows: an electrical voltage of 3 KV to apply nozzle, a solution pursing of 0.032 µl per sec, a distance of 45 mm between nozzle and substrate for 30 sec with a 0.3 M of ZTO solution. The electrical properties were obtained as follows; a mobility of 2.0 cm2/Vs, a current ratio Ion/Ioff of 105, a threshold voltage of −10 V, a subthreshold slope of 1.74 V/dec. Based on this result, more in-depth research should be performed in this specific area for further development and electronic applications.

Electrohydrodynamic Jet Printed Indium–Zinc–Oxide Thin-Film Transistors

Electrohydrodynamic (EHD) jet-printed indium-zinc-oxide thin-film transistors (TFTs) were prepared at various annealing temperatures. The EHD jet was achieved by optimizing the process parameters; such as the precursor viscosity, driving voltages, and substrate temperatures. The EHD jet-printed IZO films were characterized using a range of analytical methods. Metal oxide formation was confirmed by X-ray photoelectron spectroscopy. The EHD jet-printed IZO TFTs showed good electrical properties: a mobility of 4.8 cm2/V·s, a threshold voltage of 8.4 V, an on-to-off current ratio of 107, and a subthreshold slope of 1.2 V/dec at 400 °C. The positive and negative bias stability were also analyzed.

Screen-printed Source and Drain Electrodes for Inkjet-processed Zinc-tin-oxide Thin-film Transistor

Screen-printed source and drain electrodes were used for a spin-coated and inkjet-processed zinc-tin oxide (ZTO) TFTs for the first time. Source and drain were silver nanoparticles. Channel length was patterned using screen printing technology. Different silver nanoinks and process parameters were tested to find optimal source and drain contacts Relatively good electrical properties of a screen-printed inkjet-processed oxide TFT were obtained as follows; a mobility of 1.20 /Vs, an on-off current ratio of , a Vth of 5.4 V and a subthreshold swing of 1.5 V/dec.