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Optical Properties of LAO:Eu3+ Thin films D.Y. Medina1, S. Orozco2, R.T. Hernandez1, I. Hernandez1, C. Falcony2 1

CBI-UAM-Azcapotzalco, Av. San Pablo No 180 Col. Reynosa-Tamaulipas, C. P. 02200 México, D. F, México. 2 Depto. de Física, Fac. de Ciencias UNAM Av. Universidad 3000, Col. Copilco, D.F. México 3 Depto. de Física, CINVESTAV. Av. IPN 2508. Col. San Pedro Zacatenco, Email: [email protected] ABSTRACT Lanthanum aluminate (LaxAl1−xOy; LAO) films doped with europium were deposited on a glass substrate by Ultrasonic Spray Pyrolysis technique. Like precursor solution was used 0.04M lanthanum nitrate and 0.04M aluminum nitrate in de-ionized water, and from europium nitrate was aggregated europium to 6%mol respect to LaO. The aluminum incorporated to rare earth oxides shows a high hydration resistance, therefore the films show stability in their luminescent properties. In this work the optical and morphological properties of the films are reported in the 350-600ºC deposition range. The photoluminescent emission spectra show the characteristic peaks of the Eu3+ ion transitions: 5D0 → 7F0 (565 nm), 5D0→7F1 (596 nm), 5D0–7F2 at 615 nm and 623 nm, 5D0→7F3 (660 nm) and 5D0→7F4 (715 nm) for an excitation wavelength of 270 nm. Keywords: spray pyrolysis, film, Eu, luminescence, lanthanide INTRODUCTION Recently the rare earths (RE) doped semiconductors research has been extended because they have technological applications like visible light-emitting diodes and panel displays [1-4]. On the other hand, is well established that the RE ions exhibit smaller luminescence quenching when they are inserted in wide band gap (WBG) materials [5-7]. The LAO compounds are widely used as substrates for superconductors [8,9], but there are scarce literature about the spectroscopic properties of rare-earth ions in this host [10-14]. At the present, new low-temperature synthesis methods have been reported. The ultrasonic spray pyrolysis method is a well established process for depositing films at relatively low temperature. The main advantages of this technique are its low cost, a high deposition rate, the possibility to coat large areas, its ease of operation and the quality of the coatings obtained which can be easily scaled to industrial level [4,15,16]. EXPERIMENTAL The glass substrate was placed on a resistance heated stage and the spraying nozzle was located approximately at 6mm above the substrate surface, all enclosed in an exhaust hood. The spraying solution was 0.04M lanthanum nitrate and 0.04M aluminum nitrate in de-ionized water, and europium (6%mol respect to LaO) from europium nitrate. The carrier gas (filtered air) and the solution flow rates were 100ml / minute and 3 ml/min, respectively, with a ultrasonic nebulizer vibration of 0.9MHz, and a deposition time of 2 minutes. The substrate temperature

Mater. Res. Soc. Symp. Proc. Vol. 1275 © Materials Research Society

(Ts) during deposition was in the 350 to 600 C range; Corning 7059 glass slides were used as substrates. Measurements of photoluminescence (PL) were p