Synthesis and cathodoluminescence characterization of ZrO 2 :Er 3 þ films A. Martínez-Hernández a , J. Guzmán-Mendoza a , T. Rivera-Montalvo a,n , D. Sánchez-Guzmán a , J.C. Guzmán-Olguín a , M. García-Hipólito b , C. Falcony c a Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del Instituto Politécnico Nacional, Unidad Legaria, Av. Legaria 694,11500 México, D. F., Mexico b Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior, Cd. Universitaria, 04510 México, D. F., Mexico c Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, 07000 México, D.F., México article info Article history: Received 23 December 2013 Received in revised form 25 February 2014 Accepted 5 March 2014 Available online 14 March 2014 Keywords: ZrO 2 :Er 3 þ films Spray pyrolysis method Cathodoluminescence Metal oxides abstract Trivalent erbium doped zirconium oxide films were deposited by the ultrasonic spray pyrolysis technique. Films were deposited using zirconium tetrachloride octahydrate (ZrCl 4 O Á 8H 2 O) and erbium nitrate hexahydrate ((NO 3 ) 3 Er Á 6H 2 O) as precursors and deionized water as solvent. The dopant concentrations in the spray solution were 1, 3, 5, 10 and 15at% in ratio to zirconium content. The films were deposited on corning glass substrates at different temperatures from 400 up to 550 1C. Films deposited at temperatures lower than 400 1C were amorphous, however, as substrate temperatures are increased, the ZrO 2 films presented a better crystallinity and showed a tetragonal phase. Cathodolumi- nescence (CL) emission spectra showed bands centred at 524, 544 and 655 nm associated with the electronic transition of Er 3 þ . & 2014 Elsevier B.V. All rights reserved. 1. Introduction In the last decade zirconium oxide (ZrO 2 ) has been widely studied for its physical and chemical features such as: high crystallographic density (5.7 g/cm 3 ), high fusion point (2715 1C), wide energy gap (Eg ¼ 5.8 eV), low phonon frequency, good thermal and chemical stability [1–4]. ZrO 2 is used as an additive to enhance the oxygen storage capacity (OSC) of the CeO 2 making it an efficient OSC material [5]. These characteristics make this material a potential candidate for multiple applications such as: electronic devices, wave of guide and dosimetric devices [6–8]. When this oxide is deposited as films it has a relatively high refractive index (n ¼ 2.13). ZrO 2 combined with silicon is suggested as a Metal-Oxide-Semiconductor (MOS) structure to replace silicon oxide, which has been widely used in microelectronics applications [9–11]. Zirconium oxide has been used as luminescent matrix of rare earth and transition metals. When it is activated with trivalent rare earth ions, it achieves remarkable photo and cathodolumi- nescent characteristics [12–15]. At the present time, zirconium oxide films have been deposited by several techniques such as: Chemical Vapour Deposition (CVD), Sol–Gel (SG) [16,17], Atomic Layer Deposition (ALD), Photochemical Metal Organic Deposition (PMOD) [4], and Ultrasonic Spray Pyrolysis (USP) [10]. The USP technique is an adequate technique to prepare films of many materials, mainly oxides, sulphides, and selenides. The UPS synth- esis technique has resulted as versatile due its reactive organic and inorganic salts such as: chlorides, nitrates, acetates, acetylaceto- nates, ethoxides and butoxides dissolved on deionized water, ethanol or organic solvents [18]. The USP technique has many advantages over other synthesis methods: low cost, high deposi- tion rates, easy to operate and capability to carry out deposition on large areas. In this paper the synthesis and cathodoluminescence characterization of ZrO 2 :Er 3 þ films deposited by ultrasonic spray pyrolysis technique are reported. 2. Experimental details The ZrO 2 films were obtained using the Ultrasonic Spray Pyrolysis (USP) technique. The USP technique consists of a spray of precursor solution and it is directed onto the corning glass substrate which is previously heated, where the pyrolysis reaction is performed. Solutions of ZrCl 4 O Á 8H 2 O from Alfa-Aesar with 99.99% degree of purity and (NO 3 ) 3 Er Á 6H 2 O with 99% degree of purity were used as precursors, and deionized water as solvent. The spray solution concentration was 0.05 M and the substrate Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jlumin Journal of Luminescence http://dx.doi.org/10.1016/j.jlumin.2014.03.013 0022-2313/& 2014 Elsevier B.V. All rights reserved. n Corresponding author. E-mail address: trivera@ipn.mx (T. Rivera-Montalvo). Journal of Luminescence 153 (2014) 140–143