Soon Joo Yoon’s research while affiliated with Jeonbuk National University and other places

This work reports the impact of gamma-ray (γ-ray) irradiation-induced degradation based on the trap behaviors in amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors. By employing multiple measurement configurations via low-frequency noise and direct current I–V characterization, we quantitatively investigated the energetic distribution of subgap density-of-states in the a-IGZO channel and the spatial distribution of oxide traps (Not) in the gate insulator, respectively. Also, the qualitative analysis was performed to determine the oxygen-related defects after γ-ray irradiation using x-ray photoelectron spectroscopy. Furthermore, the validity of our results was additionally confirmed by measuring the breakdown voltage and applying positive-bias stress to the fabricated devices exposed to radiation for accelerated tests.

Correction for ‘Monolithic green-sensitive photodetectors enabled by a ZnSnN 2 /GaN nanorods/silicon double heterojunction’ by Jeong Hyeon Kim et al. , Inorg. Chem. Front. , 2025, https://doi.org/10.1039/d4qi02418d.

In this article, we investigate the effect of annealing in deuterium (D ₂ ) ambient on the performance and reliability of InGaZnO (IGZO) thin-film transistors (TFTs). We examined the current–voltage ( I – V ) characteristics, as well as the ON-state current ( I _on ), OFF-state current ( I _off ), and subthreshold slope (SS) under three different conditions: after device fabrication (as-fabricated), in a deteriorated state (after 7 days), and after D ₂ annealing. To analyze the reliability of IGZO TFTs, the oxygen vacancy ( V _O ) behavior was observed by extracting the subgap density of state (DOS) using I – V data. Quantitative and qualitative analyses of the changes in ion distribution inside the IGZO channel after D ₂ annealing were performed by X-ray photoelectron spectroscopy (XPS) and secondary-ion mass spectrometry (SIMS), respectively, both of which verified the effect of the D ₂ annealing. The validity of our results was further verified by comparing them to model parameters generated using a technology computer-aided design (TCAD) simulation.

Monolithic green-sensitive photodetectors (PDs) showed superior green sensitivity over single heterojunction-based PDs. The spectral-filtering effect significantly enhanced sensitivity, resulting in a 98-fold improvement.

This review investigates the transformative potential of neuromorphic computing in advancing biointegrated electronics, with a particular emphasis on applications in medical sensing, diagnostics, and therapeutic interventions. By examining the convergence of edge computing and neuromorphic principles, we explore how emulating the operational principles of the human brain can enhance the energy efficiency and functionality of biointegrated electronics. The review begins with an introduction to recent breakthroughs in materials and circuit designs that aim to mimic various aspects of the biological nervous system. Subsequent sections synthesize demonstrations of neuromorphic systems designed to augment the functionality of healthcare-related electronic systems, including those capable of direct signal communication with biological tissues. The neuromorphic biointegrated devices remain in a nascent stage, with a relatively limited number of publications available. The current review aims to meticulously summarize these pioneering studies to evaluate the current state and propose future directions to advance the interdisciplinary field.

The amorphous In─Ga─Zn─O (a‐IGZO) thin film transistors (TFTs) have attracted attention as a cell transistor for the next generation DRAM architecture because of its low leakage current, high mobility, and the back‐end‐of‐line (BEOL) compatibility that enables monolithic 3D (M3D) integration. IGZO‐based electronic devices used in harsh environments such as radiation exposure can be vulnerable, resulting in functional failure. Here, the behavior of subgap density‐of‐states (DOS) over full subgap range according to the impactful gamma‐ray irradiation in a‐IGZO TFTs is investigated by employing DC current–voltage (I−V) data with multiple‐wavelength light sources. To understand the origins of the radiation effect, IGZO films have been also analyzed by x‐ray photoelectron spectroscopy (XPS). Considering in‐depth electrical and chemical analysis, the unexpected increase of subthreshold leakage current caused by total ionizing dose (TID) is strongly correlated with newly discovered deep‐donor states (gDDγ(E)$g_{DD}^\gamma ( E )$) at the specific energy level. In particular, oxygen vacancies caused by the gamma‐ray irradiation give rise to undesirable electrical characteristics such as hysteresis effect and negative shift of threshold voltage (VT). Furthermore, the TCAD simulation results based on DOS model parameters are found to exhibit good agreement with experimental data and plausible explanation including (gDDγ(E)$g_{DD}^\gamma ( E )$).

The use of water-based chemistry in photolithography during semiconductor fabrication is desirable due to its cost-effectiveness and minimal environmental impact, especially considering the large scale of semiconductor production. Despite these benefits, limited research has reported successful demonstrations of water-based photopatterning, particularly for intrinsically water-soluble materials such as Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) due to significant challenges in achieving selective dissolution during the developing process. In this paper, we propose a method for the direct patterning of PEDOT:PSS in water by introducing an amphiphilic Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO, P123) block copolymer to the PEDOT:PSS film. The addition of the block copolymer enhances the stretchability of the composite film and reduces the hydrophilicity of the film surface, allowing for water absorption only after UV exposure through a photoinitiated reaction with benzophenone. We apply this technique to fabricate tactile and wearable biosensors, both of which benefit from the mechanical stretchability and transparency of PEDOT:PSS. Our method represents a promising solution for water-based photopatterning of hydrophilic materials, with potential for wider applications in semiconductor fabrication.

The rapid expansion of soft electronics and actuators necessitates the development of mechanically robust substrates possessing a unique combination of properties: high stretchability, self-healing capabilities, and favorable dielectric characteristics. This study presents a novel composite film comprising an elastic Styrene-Ethylene-Butylene-Styrene (SEBS) matrix and a high dielectric constant Polyvinylidene Fluoride (PVDF) component. A systematic investigation of its mechanical characteristics reveals exceptional stretchability, with a strain of up to 1600%, and showcases remarkable self-healing properties, which manifest upon exposure to a moderate temperature of 70 ℃. The incorporation of SEBS not only imparts mechanical resilience but also contributes to the stabilization of dielectric properties across a wide range of frequencies while the incorporation of PVDF contributes the increase of the output voltages upon pressure. The versatility of this material system holds potential for addressing a wide array of challenges in soft electronics, from conformable wearable technologies to adaptable robotic interfaces.