Journal of Luminescence 104 (2003) 47–54 Improving the efficiency of a blue-emitting phosphor by an energy transfer from Gd 3+ to Ce 3+ E.J. Bosze a , G.A. Hirata a,b , L.E. Shea-Rohwer c , J. McKittrick a, * a Department of Mechanical and Aerospace Engineering and Materials Science and Engineering Program, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0411, USA b Centro de Ciencias de la Materia Condensada, Universidad Nacional Aut ! onoma de M! exico, CP 22860, Ensenada, Baja California, Mexico c Sandia National Laboratory, Albuquerque, NM 87185-0527, USA Received 6 June 2002; received in revised form 11 November 2002; accepted 11 November 2002 Abstract The low-voltage efficiency of the blue-emitting phosphor, cerium activated yttrium silicate (Y 1m Ce m ) 2 SiO 5 , has been improved by co-activating with gadolinium, (Y 1mn Ce m Gd n ) 2 SiO 5 . Gd 3+ improves the efficiency by transferring energy to Ce 3+ , and makes this phosphor a more promising candidate for low-voltage field emission flat panel displays. Low-voltage cathodoluminescence and photoluminescence measurements were made to determine the optimum concentrations of Gd 3+ that yielded the most luminous efficient phosphor. For photoluminescence, Ce 3+ most efficiently luminesces at the excitation wavelength l ex ¼ 358nm. Co-activating with Gd 3+ did not improve the photoluminescent efficiency because Gd 3+ does not absorb at Ce 3+ excitation energy, and thus cannot transfer energy. For low-voltage cathodoluminescence, co-activating with Gd 3+ did improve the efficiency since Gd 3+ was sufficiently excited, with the optimum composition found to be (Y 0.8425 Ce 0.0075 Gd 0.15 ) 2 SiO 5 . r 2002 Elsevier Science B.V. All rights reserved. PACS: 78.55.m; 78.60.b Keywords: Cathodoluminescence; Photoluminescence; Luminescence efficiency; Energy transfer 1. Introduction Field emission displays (FED) are the next generation flat panel display design that utilizes cathodoluminescence (CL) to excite phosphors, similar to the mature cathode-ray tubes (CRTs). CRTs are large, but offer a bright screen and good contrast due to the high amount of energy, between 15 and 30 keV, the electrons impart onto the phosphor-coated screen. In FED technology, the electron gun is replaced by a matrix-addressed array of hundreds of millions of B1 mm inverted conical electron field emitter tips deposited onto a flat substrate. The distance between the emitter tips and the phosphor coated screen is greatly reduced from that distance between the electron gun and the screen in CRTs (0.1 cm compared with B45cm). Thus, the acceleration voltages are *Corresponding author. Tel.: +1-619-534-5425; fax: +1- 619-534-5698. E-mail address: jmckittrick@ucsd.edu (J. McKittrick). 0022-2313/02/$-see front matter r 2002 Elsevier Science B.V. All rights reserved. doi:10.1016/S0022-2313(02)00663-4