We report on a Pt͑8 nm͒/Rh͑200 nm͒ metallization scheme for use in low resistance and high reflectance ohmic contacts to p-GaN for use in flip chip light-emitting diodes ͑FCLED͒ applications. The thermal annealing of a Pt/Rh contact at 500°C led to linear current-voltage characteristics with a specific contact resistance of 9.0 ϫ 10 Ϫ5 ⍀ cm 2 while the as-deposited Pt/Rh contact showed nonohmic characteristics. It was also shown that the 500°C annealed contact produces a high reflectance of 62% at a wavelength of 460 nm. Auger electron spectroscopy depth profiles and glancing-angle X-ray diffraction results indicated that the low contact resistance of the annealed sample can be attributed to the formation of Ga-Pt and Ga-Rh intermetallic phases. Furthermore, the electrical performance of an FCLED with the Pt/Rh reflector scheme was superior to that of a FCLED with a Ni/Au/Ag reflector scheme.

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주제어 : 친환경 세정제, 비이온계면활성제, 정수장 스케일, 유기산, 금속산화물 용해력 Abstract : In this study, an environmental-friendly cleaning agent utilizing organic acids and various additives has been developed and applied to the field for removal of scale deposited on the cleaning beds or distribution reservoirs of the waterworks. As an analytical result of scale on the cleaning beds, we found that it consists of mainly metallic oxides such as SiO2, Al2O3, Fe2O3, and MnO. Malic acid, malonic acid, and citric acid showed relatively better solvency on Al2O3, Fe2O3, and MnO except SiO2 among various organic acids. Mixed organic acid solutions of malic acid, malonic acid, and citric acid were prepared with certain weight ratios and their solvencies on mixed metal oxides of Al2O3, Fe2O3, and MnO were investigated. The experimental results showed that an 10% mixed organic acid solution prepared with weight ratio of malic acid : malonic acid : citric acid = 6 : 2 : 2 were found to have best scale solvency power of about 29%. The formulated cleaning agents with a small amount of nonionic surfactant showed