2020 17th International Conference on Electrical Engineering, Computing Science and Automatic Control (CCE) Mexico City, Mexico. November 11-13, 2020 978-1-7281-8987-1/20/$31.00 ©2020 IEEE Photoluminescence emission under thermal annealing of Silica and Titania nanospheres arrays Carina Gutierrez Optics National Institute for Astrophysics Optics and Electronics. Puebla, Mexico. carina.gutierrez@inaoep.mx Mario Moreno Electronics National Institute for Astrophysics Optics and Electronics. Puebla, Mexico. mmoreno@inaoep.mx Ponciano Rodríguez Optics National Institute for Astrophysics Optics and Electronics. Puebla, Mexico. ponciano@inaoep.mx Leticia Tecuapetla Electronics National Institute for Astrophysics Optics and Electronics. Puebla, Mexico. tecuap@inaoep.mx Armando Hernandez Electronics National Institute for Astrophysics Optics and Electronics. Puebla, Mexico. ahdz@hotmail.com Adrian Itzmoyotl Faculty of Electronics Science Meritorious University Autonomous of Puebla Puebla, Mexico aitzmo@hotmail.com Abstract— Experimental results on the influence of the annealing time on the photoluminescence (PL) emission of silica array is presented. Bilayers of titania and silica with a thickness of 100 nm and 600 nm, respectively were uniformly deposited on crystalline silicon (c-Si) substrates, and exposed to annealing process from 0 to 60 minutes in intervals of 10 minutes at 1100°C in a nitrogen atmosphere. Our results showed that annealed samples during 30 minutes present PL emission 110 times larger than samples without annealing. Influence of the nanoparticles array distribution on the PL intensity before and after the annealing process is also presented. Keywords— Silica, Titania, nanospheres, photoluminescence, layers. I. INTRODUCTION Due to its high thermal stability, high chemical durability, low thermal expansion coefficient and adjustable refractive index, titania (TiO2) and silica (SiO2) based films have been widely used for several optics applications [1]. Moreover, the photoluminescence (PL) properties of titania and silica nanoparticles (NPs) are employed for multiple research projects and for a large number of optoelectronics and photonic applications [2]. Some optoelectronic circuits are fabricated from materials that do not emit light efficiently, which limits the integration of light sources in the system [3]. To solve this inconvenient, several techniques have been proposed to improve the efficiency of the light source, including thermal annealing. Photoluminescence (PL) and the mechanism of light emission in thermally annealed thin films have been widely studied, for example, in the silicon excess in silicon-rich oxide (SRO) films and TiO2-SiO2 films. Performance of the dependence of the PL peak energy and its intensity enhancement as a function of the annealing time was studied in Refs [4] and [5]. The studied films exhibited a PL band in the 1.4-2.1 eV range after to be exposed at 1100°C for 1, 3 and 5 hours [6]–[8]. The temperature modifies the size and structure of the nanocrystals (nCs); for low temperature (900°C) the nCs presented lower crystallinity compared with samples annealed at higher temperature (1000 and 1100°C) [2]. Increasing the size of nCs leads the PL emission at longer wavelengths (red shift). The light emission is explained according to quantum confinement model. Experimentally, it was found that the nCs average size is not increased when the films were exposed to prolonged thermal annealing. In semiconductors nanoscience, the ability to control the size and shape (i.e. nanospheres, nanopillars and nanofibres) of colloidal nanomaterials provide more flexibility and options for the design of new materials to different applications [9]. Several structures have been studied after a high temperature annealing; generally, they shown a structural transformation and an increase on the photoluminescence. Our interest is on spherical nanostructures, in particular silica and titania nanospheres. The individual characterization of these NPs are reported in previous works [10], [11]. For instance, the PL emission of silica NPs with Ce and Tb core exposed to a thermal annealing present a dependence with the particle size; after to be annealed at 700°C for 3 hours the NPs with diameter of 600 nm and 1200 nm show a PL intensity of 15000 a.u. and 45000 a.u., respectively [8]. However, there are few studies into luminescence of titania nanoparticles after an annealing