Hyungjin Park

Solution-Processed Flexible Fluorine-doped Indium Zinc Oxide Thin-Film Transistors Fabricated on Plastic Film at Low Temperature

Transparent flexible fluorine-doped indium zinc oxide (IZO:F) thin-film transistors (TFTs) were demonstrated using the spin-coating method of the metal fluoride precursor aqueous solution with annealing at 200°C for 2 hrs on polyethylene naphthalate films. The proposed thermal evolution mechanism of metal fluoride aqueous precursor solution examined by thermogravimetric analysis and Raman spectroscopy can easily explain oxide formation. The chemical composition analysed by XPS confirms that the fluorine was doped in the thin films annealed below 250°C. In the IZO:F thin films, a doped fluorine atom substitutes for an oxygen atom generating a free electron or occupies an oxygen vacancy site eliminating an electron trap site. These dual roles of the doped fluorine can enhance the mobility and improve the gate bias stability of the TFTs. Therefore, the transparent flexible IZO:F TFT shows a high mobility of up to 4.1 cm2/V·s and stable characteristics under the various gate bias and temperature stresses.

Photo-curable siloxane hybrid material fabricated by a thiol–ene reaction of sol–gel synthesized oligosiloxanes

The thiol-ene reaction of a sol-gel synthesized oligosiloxane thiol-ene mixture was processed through UV irradiation, resulting in transparency, high refractive index, good thermal stability and especially excellent electrical insulation materials. It provides new strong potential of the thiol-ene system for application in dielectric materials.

Space charge-induced unusually-high mobility of a solution-processed indium oxide thin film transistor with an ethylene glycol incorporated aluminum oxide gate dielectric

The incorporation of ethylene glycol (EG) into a high-k aluminium oxide gate dielectric layer was achieved by a solution process, leading to a distinct increase in the mobility of indium oxide TFT. Frequency-dependent capacitance originating from residual EG was examined and the accompanying effects on indium oxide TFT were studied.

Improvement of bias stability of oxyanion-incorporated aqueous sol–gel processed indium zinc oxide TFTs

Oxyanion-incorporated indium zinc oxide (IZO) TFTs exhibiting excellent bias stabilities are fabricated from aqueous IZO precursor solutions blended with a catalytic amount of inorganic acids (H2SO4, H3PO4, H3BO3). The resulting oxyanion-incorporated IZO TFTs (SO–IZO, PO–IZO, BO–IZO) exhibit improved bias stabilities under NBS, PBS, NBTS, and PBTS conditions.

Supply chain optimization involving long-term decision-making

Abstract This paper deals with the optimal design problem of multiproduct, multi-echelon supply chains for Supply Chain Management. The supply chains are composed of plants, warehouses, distribution centers, and customers. The locations of the plants and the customers are fixed. The locations and capacities of warehouses and distribution centers should be determined. The transportation and production of products should be determined, too. A mixed integer linear programming is used for the mathematical modeling. The objective is to minimize total cost of supply chains. We propose more detail modeling techniques in the cost calculations for the transportation of products and the installation of warehouses and distribution centers on the basis of the recent research on the supply network design by Tsiakis et al. (2001).

Highly improved photo-induced bias stability of sandwiched triple layer structure in sol-gel processed fluorine-doped indium zinc oxide thin film transistor

In order to improve the reliability of TFT, an Al2O3 insulating layer is inserted between active fluorine doped indium zinc oxide (IZO:F) thin films to form a sandwiched triple layer. All the thin films were fabricated via low-cost sol-gel process. Due to its large energy bandgap and high bonding energy with oxygen atoms, the Al2O3 layer acts as a photo-induced positive charge blocking layer that effectively blocks the migration of both holes and V o2+ toward the interface between the gate insulator and the semiconductor. The inserted Al2O3 triple layer exhibits a noticeably low turn on voltage shift of −0.7 V under NBIS as well as the good TFT performance with a mobility of 10.9 cm2/V ⋅ s. We anticipate that this approach can be used to solve the stability issues such as NBIS, which is caused by inescapable oxygen vacancies.