Sol-gel solution-deposited InGaZnO thin film transistors.

Thin film transistors (TFTs) fabricated by solution processing of sol-gel oxide semiconductor precursors in the group In-Ga-Zn are described. The TFT mobility varies over a wide range depending on the precursor materials, the composition, and the processing variables, with the highest mobility being about 30 cm(2)/(V s) for IZO and 20 cm(2)/(V s) for IGZO. The positive dark bias stress effect decreases markedly as the mobility increases and the high mobility devices are quite stable. The negative bias illumination stress effect is also weaker in the higher mobility TFTs, and some different characteristic properties are observed. The TFT mobility, threshold voltage, and bias stress properties are discussed in terms of the formation of self-compensated donor and acceptor states, based on the chemistry and thermodynamics of the sol-gel process.

Use of a poly(ether imide) coating to improve corrosion resistance and biocompatibility of magnesium (Mg) implant for orthopedic applications.

This study investigated the utility of poly(ether imide) (PEI) coating for improving the corrosion resistance and biocompatibility of magnesium (Mg) implants for orthopedic application. In particular, the microstructure of the PEI coating layers was controlled by the adjustment of the temperature used to dry the spin-coated wet PEI films. When a wet PEI film was dried at 4°C, a relatively thick and porous coating layer was achieved as a result of an extensive exchange of the solvent with water in a moist environment. In contrast, when a wet PEI film was dried at 70°C, a relatively thin and dense layer was created due to the faster evaporation of the solvent with a negligible exchange of the solvent with water. The porous PEI coating layer showed higher stability than did the dense one when immersed in a simulated body fluid (SBF), which was presumably attributed to the formation of chemical bonding between the PEI and the Mg substrate. Both the porous and the dense PEI coated Mg specimens showed significantly improved in vitro biocompatibility, which were assessed in terms of cell attachment, proliferation and differentiation. However, interestingly, the dense PEI coating layer showed greater cell proliferation and differentiation than did the porous layer. .

Effect of annealing titanium on in vitro bioactivity.

In order to modify titanium surfaces for various biological applications, bioactive and pure titanium oxide thin films were coated on the titanium by thermal oxidation technique. The commercially pure titanium discs after polishing were heated at 500, 550, 600, 650 and 700 degrees C, respectively, for 10 min in air or in argon. To evaluate the ability of calcium phosphate formation, samples after annealing were soaked in the Eagle's minimum essential medium solution. Surface morphology and chemical composition of the samples before or after immersion were characterized by field emission - scanning electron microscopy and energy dispersive X-ray spectrometry.

Calcium phosphate formation on nanocrystalline ZrO2 thin film prepared by using a zirconium naphthenate.

To investigate the calcium phosphate forming ability of ZrO(2) thin film, we prepared ZrO(2)/Si structure by a chemical solution deposition with a zirconium naphthenate as a starting material. Precursor sol was spin-coated onto the cleaned Si substrate and prefired at 500 degrees C for 10 min in air, followed by final annealing at 800 degrees C for 30 min in air. Surface morphology and surface roughness of the annealed layer were characterized by field emission-scanning electron microscope and atomic force microscope. After soaking for 5 days in a simulated body fluid, formation of the calcium phosphate on nanocrystalline ZrO(2) layer annealed at 800 degrees C was observed by energy dispersive X-ray spectrometer. Fourier transform infrared spectroscopy revealed that carbonate was substituted into the calcium phosphate.