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Busan, South Korea

C.R. Kesavulu,Changwon National University | Lee D.G.,Silla University | Yi S.S.,Silla University | Jang K.,Changwon National University | And 5 more authors.
Journal of Alloys and Compounds

Eu3+-activated novel alkaline earth metal (Sr and Ba) vanadate phosphors, Na(Sr0.97-x,Bax)VO4:Eu3+ 0:03 (x = 0-0.97) have been successfully synthesized using solid state reaction method and characterized through structure, morphology, elemental analysis, luminescence (excitation, emission and CIE coordinate) and decay rate properties as a function of Ba ion concentration. Phosphors show a broad excitation band (monitored for 5D0→7F 2 transition of Eu3+) in the 230-430 nm wavelength regions which make them highly suitable for GaN-based LED chips. These phosphors can be efficiently excited by near UV light and exhibit a dominant red emission at 613 nm 5D0→7F2. The decay lifetime and color coordinates were evaluated for Na(Sr,Ba)VO4:Eu 3+ phosphors. Hence, these phosphors could be a potential candidate for light emitting diodes and display applications. © 2013 Published by Elsevier B.V. Source

Kim M.,BUSANIL Science High School | Kim M.G.,BUSANIL Science High School | Kim S.R.,BUSANIL Science High School | Chung H.Y.,BUSANIL Science High School | And 5 more authors.
Journal of the Korean Physical Society

We investigate the surface modification of a germanium epitaxial layer grown on a silicon substrate by means of an atmospheric-pressure plasma jet. The plasma jet contains a large density of highly reactive radicals, as confirmed by optical emission spectra. The plasma jet with a nozzle with a round end has a higher current level compared to cylindrical and pencil-shaped nozzles, indicating the usefulness of this plasma jet for semiconductor processing. Raman spectra reveal a significant modification of the germanium surface under exposure to an atmospheric pressure plasma jet even for 1 min. The first-order Raman peak at 320 cm-1 has an asymmetric shoulder on the low-frequency side, which can be attributed to amorphization/oxidation of the germanium layer due to highly reactive radicals. The rapid surface change under short-time exposure indicates the practicality of the plasma jet for semiconductor processing. © 2013 The Korean Physical Society. Source

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