김형태 교수

Visible light can be detected using an indium-gallium-zinc oxide (IGZO)-based phototransistor, with a selenium capping layer (SCL) that functions as a visible light absorption layer. Selenium (Se) exhibits photoconductive properties as its conductivity increases with illumination. We report an IGZO phototransistor with an SCL (SCL/IGZO phototransistor) that demonstrated optimal photoresponse characteristics when the SCL was 150 nm thick. The SCL/IGZO phototransistor exhibited a photoresponsivity

Abstract Neurodegenerative disorders are challenging issues for initial diagnosis and cure. False signals from neurons that make up the brain must be corrected. To treat neurodegenerative diseases, neuromorphic devices are inserted into the body and connected to nerves. However, there are major concerns regarding implanting these devices into living bodies, that is, toxicity caused by the materials and the need for an additional operation to remove the device after treatment. In this research, a

We investigated a facile fabrication method, which is an insertion of a carrier-induced interlayer (CII) between the oxygen-rich a-IGZO channel and the gate insulator to improve the electrical characteristics and stability of amorphous indium-gallium-zinc-oxide thin-film transistors (a-IGZO TFTs). The a-IGZO channel is deposited with additional oxygen gas flow during a-IGZO channel deposition to improve the stability of the a-IGZO TFTs. The CII is a less than 10 nm thick deposited thin film that

This paper proposes a novel pixel circuit and driving scheme that adopts low-temperature polycrystalline silicon and oxide thin-film transistors (LTPO TFTs) for mobile devices using active-matrix organic light-emitting diode (AMOLED) displays. The proposed pixel circuit and driving scheme provide uniform luminance and render flicker invisible at variable refresh rates (VRRs) from 1 to 120 Hz. Using the proposed pixel circuit with extended compensation time (tCOMP) improves the luminance uniformi

A simple fabrication method for homojunction-structured Al-doped indium-tin oxide (ITO) thin-film transistors (TFTs) using an electrohydrodynamic (EHD) jet-printed Al₂O₃ passivation layer with specific line (<i>W</i>_Al₂O₃) is proposed. After EHD jet printing, the specific region of the ITO film below the Al₂O₃ passivation layer changes from a conducting electrode to a semiconducting channel layer simultaneously upon the

We considered the issue of color mixing from the viewpoint of gray scale images and investigated the effect of the mixed light. The goal of this study was to improve the quality of the grey scale images by using mixed RGB illumination. The mixing mechanism and image quality were formulized and applied to a machine vision system with an RGB mixer. The RGB mixer was made of RGB LEDs, a power AMP, a mixing chamber, and a bundle of optical fibers. The intensity of the RGB light was adjusted by varyi

The capacity of battery energy storage systems (BESS) is expected to increase for power system applications. However, as the cost of BESS is high, economic feasibility must be considered when using BESS in grid applications. Load leveling with BESS is one such application for which the economic implications have been analyzed in the literature. However, these studies do not sufficiently consider the fact that the leveled loads will lead to a change in electricity prices, thereby modifying chargi

Abstract A facile method is presented involving a reducing agent, sodium dithionite (Na 2 S 2 O 4 ), to control the photoresponse characteristics of oxide semiconductors that detect visible‐light. The method exhibits extraordinary potential for fabricating a diverse range of optoelectronic devices. Due to its weak S–S bond, Na 2 S 2 O 4 generates excessive subgap states and oxygen vacancies in hafnium–indium–gallium–zinc oxide (HIGZO) thin‐film during the reduction treatment (RDT). It is achieva

We proposed a novel material named sodium hypochlorite (NaClO) solution as a source of activation for amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). We reduced the activation temperature from 300 to 150 °C using NaClO solution (concentration: 50%) and obtained satisfactory electrical characteristics of a-IGZO TFTs. The field-effect mobility, threshold voltage, on/off ratio, subthreshold swing, and threshold voltage (<i>V</i>_th) shift under negative bias ill

We propose the introduction of a magnesium oxide (MgO_<i>x</i>) layer to reduce the temperature required for the activation of indium gallium zinc oxide (IGZO) thin films. By incorporating the MgO_<i>x</i> layer between the IGZO channel layer and the gate insulator layer, the required activation temperature is lowered from 300 to 200 °C while enhancing the electrical performance of the IGZO thin-film transistor (TFT). Specifically, the field effect mobility is improved from 6

In a previous work, magneto-rheological (MR) dampers were originally designed and implemented for reducing the vertical low-frequency vibration occurring in precise semi-conductor manufacturing equipment. To reduce the vibrations, an isolator levitated the manufacturing machine from the floor using pneumatic pressure which cut off the external vibration, while the MR damper was used to decrease the transient response of the isolator. However, it has been found that the MR damper also provides a

Abstract Demand for increased scalability of oxide thin‐film transistors (TFTs) continues to rise, along with the need for ever‐higher integration densities and driving currents. However, the undesirable channel length ( L CH )‐dependency renders short channels difficult. To overcome such behavior in back‐channel etched devices, back‐channel interface engineering using commercially favorable silicon oxide (SiO x ) and the effects thereof on the electrical characteristics of fully integrated TFTs