Kyung-Taek Kim

The Influence of the Hafnium Doping on Negative Bias Stability in Zinc Oxide Thin Film Transistor

The influence of hafnium doping on negative bias temperature instability in zinc oxide thin film transistors (TFTs) was investigated. The hafnium zinc oxide TFTs showed that the turn-on voltage (V ON ) shifted from -2 to -7 V with negligible changes in the subthreshold swing and field effect mobility (μ FE ) after a time of total stress. The enhanced improvement of the V ON shift was attributed to the reduction in interface trap density, which might result from the suppression of oxygen vacancy related defects due to the role of Hf ions.

Amorphous Indium Gallium Zinc Oxide Semiconductor Thin Film Transistors Using O2 Plasma Treatment on the SiNx Gate Insulator

In this study, we investigated the role of processing parameters on the electrical characteristics of amorphous In–Ga–Zn–O (a-IGZO) thin film transistors (TFTs) fabricated using DC magnetron sputtering at room temperature. Processing parameters including the oxygen partial pressure, annealing temperature, and channel thickness have a great influence on TFT performance and better devices are obtained at a low oxygen partial pressure, annealing at 200 °C, and a low channel thickness. We attempted to improve the a-IGZO TFT performance and stability under a gate bias stress using O2 plasma treatment. With an O2 plasma treated gate insulator, remarkable properties including excellent bias stability as well as a field effect mobility (µFE) of 11.5 cm2 V-1 s-1, a subthreshold swing (S) of 0.59 V/decade, a turn-on voltage (VON) of -1.3 V, and an on/off current ratio (ION/IOFF) of 105 were achieved.

Water Vapor Permeation Properties of Al 2 O 3 /TiO 2 Passivation Layer Deposited by Atomic Layer Deposition

In this study, and films was deposited on to PES (poly(ethersulfon) substrate by using atomic layer deposition as functions of deposition temperature and plasma power. The density and carbon contents of and films was changed by varying process conditions. High density thin films was achieved through optimizing the process conditions. Buffer layer was deposited prior to the processing of upper thin films to avoid PES surface destruction during the high power plasma process and to enhances the tortuous path for water vapor permeation for the defect decoupling effect. The water vapor transmission rate by using MOCON test was investigated to analyze the effect. Water vaper permeation properties was improved by using the inorganic multi-layer passivation layer and activation energy of the water vapor permeation was increased.

Microstructure and properties of cross-roll rolled and heat treated metastable TiNbSn alloy.

A (Ti-35mass%Nb)-4mass%Sn alloy was cross-roll rolled with a reduction ratio of 70% in which the roll axes are tilted by ± 5 degrees away from the transverse direction of the rolled sample and then aged at 250 degrees C for 2 h. Cross-roll rolling was found to increase yield strength and Youngs modulus, simultaneously. Yield strength was higher in cross-roll rolled than in conventionally rolled at same reduction ratio. Yield and tensile strength further increased by a low temperature ageing by ψ precipitation hardening and microstructure refinement. Yield and tensile strength of the aged 70% cross-roll rolled sample were higher than those of the aged 70% conventionally rolled one.

Phosphorus Doping Effect in a Zinc Oxide Channel Layer to Improve the Performance of Oxide Thin-Film Transistors

In this study, we fabricated phosphorus-doped zinc oxide-based thin-film transistors (TFTs) using direct current (DC) magnetron sputtering at a relatively low temperature of 100°C. To improve the TFT device performance, including field-effect mobility and bias stress stability, phosphorus dopants were employed to suppress the generation of intrinsic defects in the ZnO-based semiconductor. The positive and negative bias stress stabilities were dramatically improved by introducing the phosphorus dopants, which could prevent turn-on voltage (VON) shift in the TFTs caused by charge trapping within the active channel layer. The study showed that phosphorus doping in ZnO was an effective method to control the electrical properties of the active channel layers and improve the bias stress stability of oxide-based TFTs.

The influence of the SiO[sub 2] interlayer on transfer characteristic in tin oxide thin film transistor

In this article, we report the fabrication on SnO2 thin film transistors (TFTs) fabricated by DC sputtering system. SnO2 based TFTs have been reported previously, and all the TFTs operate depletion‐mode, requiring the application of a gate voltage to turn it off. In contrast to previously reports, the SnO2 TFT reported herein operates as an enhancement‐mode device, requiring the application of a gate voltage to turn the device on. Furthermore, we introduce an hafnium‐tin oxide (HfSnO) semiconductor materials that have been developed for use as p‐channel TFTs.