Eun Ae Jung

Germanium Compounds Containing Ge═E Double Bonds (E = S, Se, Te) as Single-Source Precursors for Germanium Chalcogenide Materials

New germanium chalcogenide precursors, S═Ge(dmamp)2 (3), S═Ge(dmampS)2 (4), Se═Ge(dmamp)2 (5), Se═Ge(dmampS)2 (6), Te═Ge(dmamp)2 (7), and Te═Ge(dmampS)2 (8), were synthesized from Ge(dmamp)2 (1) and Ge(dmampS)2 (2) using sulfur, selenium, and tellurium powders (dmamp = 1-dimethylamino-2-methyl-2-propanolate, dmampS = 1-dimethylamino-2-methylpropane-2-thiolate). Complexes 1 and 2 were synthesized from metathesis reactions of GeCl2·dioxane with 2 equiv of aminoalkoxide or aminothiolate ligands. Thermogravimetric analysis of complex 1 displayed good thermal stability and volatility. The molecular structures of complexes 2-8 from X-ray single crystallography showed distorted trigonal bipyramidal geometry at the germanium centers. Germanium chalcogenide materials (GeSe and GeTe) were obtained from the thermal decomposition of complexes 5, 6, and 8 in hexadecane. X-ray diffraction patterns exhibited that GeSe and GeTe had orthorhombic and rhombohedral phases, respectively. This study affords a facile method to easily prepare germanium chalcogenide materials using well-designed and stable complexes by thermal decomposition of single-source precursors in solution.

Liquid Crystal Alignment Properties of Inorganic SiO2 Layers Prepared by Reactive Sputtering in Nitrogen-Argon Mixtures

According to the advent of ubiquitous world, the requirement for the mobile information devices with high display quality and compact device size is surprisingly increased. Among the diverse candidates for this mobile display system for mobile devices, Liquid Crystal on Silicon (LCoS) is the most competitive device due to the high aperture ratio and simple fabrication process. The inorganic liquid crystal (LC) alignment layers are widely used for LCoS devices because of the thermal and photochemical stability. In this work, the reactive sputtering was selected for the preparation method of inorganic LC alignment layers. The nitrogen (N2) gas had the effect on the deposition process of SiO2 and the surface morphology of SiO2 thin layers were affected by the N2 mixing ratio of sputtering gas. In addition, the LC alignment properties on SiO2 thin layer were also closely related with the N2 mixing ratio and other sputtering conditions. In the case of high RF power of reactive sputtering, the N2 mixing ratio has little effect on the LC alignment on SiO2 thin layers. However, in the case of low RF power of reactive sputtering, the LC alignment properties were enfeebled by increasing the N2 mixing ratio. This result might be attributed to the change of the surface morphology of inorganic SiO2 thin layers.