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Concerning horizontally direct growth technology, graphite material with excellent thermal and chemical resistance is frequently used as both the crucible and the substrate in equipment operated at high temperatures. However, this can cause a major problem, namely, contamination due to the carbon and metallic impurities derived from graphite components. This study presents the experimental findings on a method of preventing the incorporation of unintended impurities into the silicon wafer by modifying the surface of the graphite. Coating the crucible and substrate with silicon carbide (SiC) could significantly reduce carbon (1.5 × 1017 atom/cm3) and metallic (undetected under analysis resolution) contamination by suppressing physical contact between the silicon melt and the graphite. It is expected that the purity of the silicon wafer will be improved to meet the demand for next-generation solar cell production with the optimum growth conditions required for obtaining the desired property of the silicon wafer.

A homogeneous Eu2W2O9 phase with small grains (∼4.0μm) was formed for the specimens fired below 1175°C. As the firing temperature was increased above 1150°C, grain growth occurred and the grain shape changed from faceted to round. The excitation spectra of the Eu2W2O9 phosphor were similar to those of the Eu2(WO4)3 phosphor, but the absorption band due to the O2−→W6+ ligand to metal charge transfer was shifted to lower energies and the 7Fo→5H3 and 7Fo→5F2,4 transitions were not found. The intensity of the excitation and emission spectra of the Eu2W2O9 phosphor considerably increased with increasing firing temperature, due to the increased grain size and changed grain shape. The intensity of the red emission band of the Eu2W2O9 phosphor was higher than that of the Eu2(WO4)3 phosphor. Moreover, the addition of LiCl to the Eu2W2O9 phosphors considerably enhanced the intensity of their emission spectra, probably due to the increased grain size. Therefore, LiCl-added, Eu2W2O9 phosphor is a promising candidate material for red color emission.

Eu2+-doped α-sialon phosphor was synthesized and structures and various luminescence properties were studied. High crystalline Ca0.8Al2.8Si9.2O1.169N14.94 phase was successively obtained for undoped and Eu2+-doped samples. Eu2+-doped α-sialon phosphor exhibited wide absorption in ultra violet (UV) and visible range, and high broad emission band peaking at from 570 to 582 nm. The optimum compositions and process conditions was obtained from 0.75 mol% Eu2+–doped Ca0.8Al2.8Si9.2O1.169N14.94 fired at 1650 °C for 2 h in 30% H2–70% N2 atm. In addition, fabrication of UV-light emitting diode (LED) lamp using this phosphor was conducted and the optical properties were measured. Relative quantum efficiency of the phosphor and luminous efficiency of the lamp were 83.66% and 35.28 lm/W, respectively. Those results indicated that Eu2+-doped α-sialon phosphor in this study was a good candidate for UV-LED light source.

BaTi4O9 thin films were grown on a Pt/Ti/SiO2/Si substrate using RF magnetron sputtering. A homogeneous BaTi4O9 crystalline phase developed in the films deposited at 550∘C and annealed above 850∘C. When the thickness of the film was reduced, the capacitance density and leakage current density increased. Furthermore, the dielectric constant was observed to decrease with decreasing film thickness. The BaTi4O9 film with a thickness of 62 nm exhibited excellent dielectric and electrical properties, with a capacitance density of 4.612 fF/μm2 and a dissipation factor of 0.26% at 100 kHz. Similar results were also obtained in the RF frequency range (1–6 GHz). A low leakage current density of 1.0 × 10−9 A/cm2 was achieved at ± 2 V, as well as small voltage and temperature coefficients of capacitance of 40.05 ppm/V2 and –92.157 ppm/∘C, respectively, at 100 kHz.