J. W. Bae

Effect of N2O Plasma Treatment on the Performance of ZnO TFTs

Postfabrication rapid thermal annealing (RTA) and subsequent nitrous oxide (N 2 O) plasma treatment improved the performance of zinc oxide (ZnO) thin-film transistors (TFTs) in terms of off current and on/off current ratio by almost 2 orders of magnitude. The off current of 2 × 10 -8 A and on/off current ratio of 3 × 10 3 obtained after RTA were improved to 10 -10 A and 10 5 , respectively, by the subsequent N 2 O plasma treatment. X-ray photoelectron spectroscopy analysis of the TFT samples showed that the RTA-treated ZnO surface had more oxygen vacancies as compared to as-deposited samples, and the oxygen vacancies at the surface of RTA-treated ZnO were reduced by subsequent N 2 O plasma treatment. The reduction of oxygen vacancies at the top region of the ZnO channel is the cause of better off current and on/off current ratio of the TFTs.

Doped-Fluorine on Electrical and Optical Properties of Tin Oxide Films Grown by Ozone-Assisted Thermal CVD

Transparent conductive fluorine-doped tin oxide (FTO, SnO 2 :F) films were grown using a low-pressure metallorganic chemical vapor deposition (LP-MOCVD) with tetramethyltin (TMT), oxygen containing 2.96 mol % ozone (O 3 ), and hydrofluoric acid (HF) as a dopant. Using ozone contained oxygen instead of pure oxygen, the substrate temperature could be reduced by ∼ 100°C while maintaining a growth rate similar to that of tin oxide film. Growth rate of FTO film increased with the flow rate of TMT, however, adherence strength between the film and glass decreased. Resistivity of FTO thin films decreased with the TMT and HF flows over most of ranges investigated, while the resistivity increased rapidly with respect to excessive flow of the TMT over 300 seem. Optical transmittance of FTO film was about 80% at 550 nm, and the variation as a function of HF flow rate was not significant. FTO film prepared at an optimum condition showed a minimum resistivity of 1.09 X 10 -3 Ω cm, a mobility of 19 cm 2 /Vs, and a carrier concentration of 3.05 X 10 20 cm -3 .

Development of a low angle forward reflected neutral oxygen beam for materials processing

Abstract In the fabrication of new silicon-based devices any process-related damage such as electrical charging and surface modification, remaining during the processing, may cause problems due to the size limitation of the devices. Therefore, less damaging etching processes are required. In this study, a neutral oxygen beam was formed using a low angle forward reflected neutral beam technique and studied to determine the possibility of it being used as an anisotropic etching technique without charging. The degree of neutralization and etch characteristics were also investigated. When an ion beam was reflected at a reflection angle

Atomic layer etching of InP using a low angle forward reflected Ne neutral beam

In this study, the atomic layer etching characteristics and the etch mechanism of (100) InP as functions of Cl2 pressure and Ne neutral beam irradiation dose were investigated. When Cl2 pressure and Ne neutral beam irradiation dose were lower than the critical values of 0.4mTorr and 7.2×1015at.∕cm2cycle, respectively, the InP etch rate (A/cycle) and the InP surface roughness varied with Cl2 pressure and Ne neutral beam irradiation dose. However, when the Cl2 pressure and Ne neutral beam irradiation dose were higher than the critical values, the InP etch rate remained as 1.47A∕cycle, corresponding to one monolayer per cycle, and the surface roughness and the surface stoichiometry remained similar to those of InP before etching.

HPLC Determination of tolperisone in human plasma

A simple high performance liquid chromatographic (HPLC) method was developed for the determination of tolperisone in human plasma. Tolperisone and internal standard (chlorphenesin) were isolated from 1 mL of plasma using 8 mL of dichlormethane. The organic phase was collected and evaporated under nitrogen gas. The residue was then reconstituted with 300 mL aliquot of mobile phase and a 100 mL aliquot was injected onto the C18 reverse-phased column. The mobile phase, 45% methanol containing 1% glacial acetic acid and 0.05% 1-hexanesulfonic acid was run at a flow rate of 1 mL/min. The column effluent was monitored using UV detector at 260 nm. The retention times for tolperisone and the internal standard were approximately 7.1 and 8.4 min, respectively. The standard curve was linear with minimal intra-day and inter-day variability. The quantification limit of tolperisone in human plasma was 10 ng/mL. The proposed method has been applied to the determination of pharmacokinetic profile of tolperisone in Koreans. The Tmax of tolperisone in Koreans (0.94±0.42 h) was not significantly differ from that reported in Europeans (0.5–1 h), but the mean half-life in Koreans (1.14±0.27 h) was shorter than that in Europeans (2.56±0.2 h). The proposed HPLC method is simple, accurate, reproducible and suitable for pharmacokinetic study of tolperisone.

Properties of amorphous tin-doped indium oxide thin films deposited by O2/Ar mixture ion beam-assisted system at room temperature

Abstract Highly transparent and conductive thin films of tin-doped indium oxide (ITO) on glass substrates were grown by the ion beam-assisted deposition (IBAD) technique without any substrate heating. X-Ray diffraction investigations indicated that all films have an amorphous structure and no other crystalline phases. The addition of Ar to O 2 flow and the increased energy of incident ions were found to reduce the resistivity of the grown films. Observed decrease in the resistivity was attributed to the increase in the carrier concentration. In the optimal growth conditions at room temperature, we obtained the electrical resistivity of 4.6×10 −4 Ω-cm, visible transmittance (at λ=550 nm) ≥90%, and optical direct band gap energy of ≅3.75 eV.

Effects of oxygen radical on the properties of indium tin oxide thin films deposited at room temperature by oxygen ion beam assisted evaporation

Abstract In this study, ITO films were deposited by an oxygen ion beam assisted evaporation technique on glass and polycarbonate substrates at room temperature and the effects of oxygen radical on the properties of ITO thin films were investigated. To generate oxygen radicals, in addition to one oxygen ion gun irradiating oxygen ions to the substrate during the ITO deposition, a separate oxygen ion gun was used without applying any voltage to acceleration grid and extraction grid while varying rf power to the ion gun. The increase of rf power to the gun increased the number of oxygen radicals. The increase of oxygen radicals to the oxygen ion beam assisted evaporation of ITO increased the optical transmittance of the ITO deposited on both glass and polycarbonate substrates. The conductivity of the deposited ITO also increased with the increase of oxygen radicals, however, too many oxygen radicals decreased the conductivity of the ITO. Hall measurement showed that the change of the carrier concentration in the film was responsible for the change of the resistivity. The increase of optical transmittance and the change of electrical conductivity with the increase of oxygen radicals were related to the oxygen incorporation to the deposited ITO thin film. ITO deposited on the polycarbonate substrate showed a little lower optical transmittance and conductivity possibly due to the higher surface roughness of the substrate. We were able to obtain room temperature ITO thin film on glass with 5.5×10 −4 Ωcm and above 85% transmittance (at 550 nm) and that on polycarbonate with 6.0×10 −4 Ωcm and approximately 85% transmittance (at 550 nm).

Effects of CYP2C9*1/*13 on the pharmacokinetics and pharmacodynamics of meloxicam

AIMS To determine the effects of the CYP2C9*1/*13 genotype on the pharmacokinetics and pharmacodynamics of meloxicam in Korean subjects. METHODS Meloxicam (15 mg) was orally administered to 21 healthy Korean volunteers with either the CYP2C9*1/*1 or the CYP2C9*1/*13 genotype. Plasma meloxicam concentrations were analysed by HPLC-UV for 72 h after drug administration. The pharmacodynamic effects of meloxicam were determined by measuring TXB(2) generated in blood. RESULTS The AUC(0,∞) and C(max) of meloxicam were 2.43- and 1.46-fold higher in the CYP2C9*1/*13 group than in the CYP2C9*1/*1 group, respectively. The oral clearance of meloxicam was significantly lower in the CYP2C9*1/*13 group (37.9% of wild type) than in the CYP2C9*1/*1 group. The t(1/2) of meloxicam was 1.84-fold longer in the CYP2C9*1/*13 group than in the CYP2C9*1/*1 group. The rate of TXB(2) production was significantly lower in the CYP2C9*1/*13 group than in the CYP2C9*1/*1 group. CONCLUSIONS The CYP2C9*1/*13 genotype is associated with decreased metabolism and increased pharmacodynamic effects of meloxicam.

Low angle forward reflected neutral beam source and its applications

As one of the many nano-device fabrication techniques employed in the semiconductor industry, neutral beams are being examined using various methods to solve possible charge-related problems that occur during device processing. This review introduces a neutral beam generated by surface neutralization of an ion beam using a low angle forward reflection technique and explains its application to various areas such as surface treatments and etching. The neutralization efficiency of an ion beam using a low angle forward reflection technique was approximately 99.7%. When a metal-oxide-semiconductor device was etched using a reactive neutral beam, it was confirmed that charge-related problems such as aspect-ratio-dependent etching and gate oxide charging could be removed using reactive neutral beam etching instead of conventional reactive ion etching. Neutral beams can be beneficial to other devices such as the III-V device and field emission device.

Characterization of Yttria‐Stabilized Zirconia Thin Films Prepared by Radio Frequency Magnetron Sputtering for a Combustion Control Oxygen Sensor

8 mol %-yttria-stabilized zirconia (YSZ) thin films as an oxygen ion conductor were deposited by radio frequency magnetron sputtering, and the oxygen gas sensing properties of YSZ were investigated using the structure of SiO 2 substrate/Ni-NiO/Pt/YSZ/Pt. X-ray diffractometry was employed to study the structure of YSZ and Ni-NiO films, and energy dispersion X-ray was used to investigate the composition of Ni-NiO thin films. The gas-sensing test was carried out for a SiO 2/Ni-NiO/Pt/YSZ/Pt film structure exposed to oxygen-controlled environments. The steady-state electromotive force (EMF) values were measured as a function of oxygen partial pressure (pO2 ; 1.013 3 10 3 to 1.013 3 10 5 Pa) and operating temperature (573 to 973 K). The fabricated gas sensor cells showed good oxygen sensing properties at the temperature range from 673 to 773 K. However, the sensors were unstable at the operational temperatures above 873 K possibly due to the enhanced interdiffusion of the materials in the multilayer. Also the operation of the sensor at temperatures below 573 K was not good because the temperature was not sufficient to cause ionic conduction in the cell. At the optimum temperature range, the experimental EMF values measured as a function of oxygen partial pressure were close to the theoretically calculated EMF values.