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Cerium Doped Garnet Phosphors for Application in White GaN-based LEDs

Published online by Cambridge University Press:  21 March 2011

Jennifer L. Wu ,
Steven P. Denbaars ,
Vojislav Srdanov  and
Henry Weinberg
Jennifer L. Wu
Affiliation:
Department of Chemical Engineering, University of California, Santa Barbara Santa Barbara, CA, 93106
Steven P. Denbaars
Affiliation:
Department of Materials, University of California, Santa Barbara Santa Barbara, CA, 93106
Vojislav Srdanov
Affiliation:
Center for Polymers and Organic Solids, University of California, Santa Barbara Santa Barbara, CA, 93106
Henry Weinberg
Affiliation:
Symyx Technologies, 3100 Central Expressway Santa Clara, CA, 95051
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Abstract

Recently, renewed interest has emerged for the development of visible light, down-converting phosphors for application in white light emitting diodes (LEDs). In such devices, a blue GaN LED can act as a primary light source, serving as an efficient pump to excite photoluminescence in a phosphor with subsequent emission occurring at lower energies. The combination of blue light from the LED chip and emission from the phosphor(s) produces white light. It was recently reported that a combinatorial approach to synthesize and screen potential inorganic phosphors for use in white LEDs could aid in identifying improved phosphors for blue to yellow down conversion. Solid state thin-film arrays (libraries) based on the garnet structure (A1−x,Bx)3−z(C1−y,Dy)5O12:Ce3+z, where A, B = Y, Gd, Lu, La; C., D = Al, Ga; x and y = 0 to 1.0; and z = 0.03, were synthesized, and x-ray diffraction was used to select library samples of the crystalline garnet phase. Libraries of these various garnets were then characterized spectroscopically and their properties compared to traditionally prepared bulk powder phosphors of similar composition. Emission and excitation trends show that as larger cations are substituted for Y (A = Y), emission and excitation are red-shifted and as larger cations are substituted for Al (C = Al), emission and excitation are blue-shifted. If smaller cations are substituted for Y and Al an opposite trend is observed. Temperature dependence photoluminescence measurements and emission/excitation trends are also examined.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 667: Symposium G – Luminescence and Luminescent Materials , 2001 , G5.1
Copyright
Copyright © Materials Research Society 2001

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References

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