Hyo-Jung Kim

Abstract Solution processing, including printing technology, is a promising technique for oxide thin‐film transistor (TFTs) fabrication because it tends to be a cost‐effective process with high composition controllability and high throughput. However, solution‐processed oxide TFTs are limited by low‐performance and stability issues, which require high‐temperature annealing. This high thermal budget in the fabrication process inhibits oxide TFTs from being applied to flexible electronics. There h

Metal oxide thin-film transistors have been continuously researched and mass-produced in the display industry. However, their phototransistors are still in their infancy. In particular, utilizing metal oxide semiconductors as phototransistors is difficult because of the limited light absorption wavelength range and persistent photocurrent (PPC) phenomenon. Numerous studies have attempted to improve the detectable light wavelength range and the PPC phenomenon. Here, recent studies on metal oxide

High-pressure annealing (HPA) affected the thermodynamics of the formation of a solution-processed oxide film through the simultaneous modification of thermal decomposition and compression, and enabled the use of lower annealing temperatures, which was favourable for device implementation. HPA also reduced the film thickness and decreased the porosity, resulting in enhanced device characteristics at low temperature. Surface and depth profile characterization using X-ray reflectivity (XRR), X-ray

Abstract Resistive random access memory (RRAM) devices are fabricated through a simple solution process using glucose, which is a natural biomaterial for the switching layer of RRAM. The fabricated glucose‐based RRAM device shows nonvolatile bipolar resistive switching behavior, with a switching window of 10 3 . In addition, the endurance and data retention capability of glucose‐based RRAM exhibit stable characteristics up to 100 consecutive cycles and 10 4 s under constant voltage stress at 0.3

Based on the previously elucidated super lateral growth phenomenon, we have developed an excimer-laser-crystallization method that produces large-grained and grain-boundary- location-controlled Si films on SiO2 and which possesses a wide processing window. For the set of experiments reported in this letter, a patterned SiO2 capping layer on top of Si films is utilized as an anti-reflective coating in order to induce artificially controlled super-lateral growth in the film upon being irradiated w

We investigated the formation of ultraviolet (UV)-assisted directly patternable solution-processed oxide semiconductor films and successfully fabricated thin-film transistors (TFTs) based on these films. An InGaZnO (IGZO) solution that was modified chemically with benzoylacetone (BzAc), whose chelate rings decomposed via a π-π* transition as result of UV irradiation, was used for the direct patterning. A TFT was fabricated using the directly patterned IGZO film, and it had better electrical char

Neuromorphic engineering, a methodology for emulating synaptic functions or neural systems, has attracted tremendous attention for achieving next-generation artificial intelligence technologies in the field of electronics and photonics. However, to emulate human visual memory, an active pixel sensor array for neuromorphic photonics has yet to be demonstrated, even though it can implement an artificial neuron array in hardware because individual pixels can act as artificial neurons. Here, we pres

Indium-gallium-zinc oxide (IGZO) films, deposited by sputtering at room temperature, still require activation to achieve satisfactory semiconductor characteristics. Thermal treatment is typically carried out at temperatures above 300 °C. Here, we propose activating sputter- processed IGZO films using simultaneous ultraviolet and thermal (SUT) treatments to decrease the required temperature and enhance their electrical characteristics and stability. SUT treatment effectively decreased the amount

Abstract We investigated the role of Ga in solution‐processed InGaZnO thin film transistors (TFTs). The incorporation of Ga into a InZnO compound system results in a decrease in the carrier concentration of the films and an off‐current of TFTs. This is a result of the Ga ions forming stronger chemical bonds with oxygen, as compared to the Zn and In ions, acting as a carrier suppressor. It was verified, using X‐ray photoelectron spectroscopy (XPS), that the vacancy‐related oxygen 1s peak was decr

We investigated the use of high-pressure gases as an activation energy source for amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs). High-pressure annealing (HPA) in nitrogen (N2) and oxygen (O2) gases was applied to activate a-IGZO TFTs at 100 °C at pressures in the range from 0.5 to 4 MPa. Activation of the a-IGZO TFTs during HPA is attributed to the effect of the high-pressure environment, so that the activation energy is supplied from the kinetic energy of the gas mol

Thin-film transistors (TFTs) with multistacked active layers (MSALs) have been studied to improve their electrical performance. The performance enhancement with MSALs has been attributed to higher film density in the effective channel; the density was higher because the porosities of the sublayers were reduced by filling with solution. The proposed TFT with MSALs exhibited an enhanced field-effect mobility of 2.17 cm(2)/(V s) and a threshold voltage shift under positive bias stress of 8.2 V, com

In this study, we investigated hybrid bulk heterojunction organic solar cells containing ZnO nanoparticles blended with poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) and having poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) or N,N-dimethylformamide (DMF)-modulated PEDOT:PSS buffer layers. The reference cell, which had a P3HT:PCBM active layer sandwiched between ITO\PEDOT:PSS and LiF\Al electrodes, exhibited an efficiency of 1.55%. The ZnO nano

We have investigated the effect of hydrogen peroxide (H2O2) on negative bias stress (NBS) stability of solution-processed amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). The instability of solution-processed a-IGZO TFTs under NBS is attributed to intrinsic oxygen vacancy defects (Vo) and organic chemical-induced defects, such as pores, pin holes, and organic residues. In this respect, we added H2O2 into an indium-gallium-zinc oxide solution to reduce the defects withou

We developed a method to improve the electrical performance and stability of passivated amorphous In-Ga-Zn-O thin-film transistors by simultaneous ultraviolet and thermal (SUT) treatment. SUT treatment was carried out on fully fabricated thin-film transistors, including deposited source/drain and passivation layers. Ultraviolet (UV) irradiation disassociated weak and diatomic chemical bonds and generated defects, and simultaneous thermal annealing rearranged the defects. The SUT treatment promot