Electroluminescent devices (ELD) based on junctions of indium doped zinc oxide (ZnO:In) and porous silicon layers (PSL) are presented in this work. PSL with different thicknesses and photoluminescent emission, around 680？nm, were obtained by anodic etching. PSL were coated with a ZnO:In film which was obtained by ultrasonic spray pyrolysis technique. Once obtained, this structure was optically and electrically characterized. When the devices were electrically polarized they showed stable electroluminescence (EL) which was presented as dots scattered over the surface. These dots can be seen with the naked eye. The observed EL goes from the 410 to 1100？nm, which is formed by different emission bands. The EL emission in the visible region was around 400 to 750？nm, and the emission corresponding to the infrared part covers the 750 to 1150？nm. The electrical characterization was carried out by current-voltage curves (I-V) which show a rectifying behavior of the devices. Observed electroluminescent dots are associated with the electron-hole injection into quantized states in PS as well as the emission from the ZnO:In film. 1. Introduction Crystalline silicon (c-Si) has been a vital material for the development of the microelectronics industry; however, it is an indirect band semiconductor so that it limits its application to the optoelectronics industry. Nevertheless, the discovery of visible luminescence at room temperature of the porous silicon (PS) has reopened the possibility to obtain electroluminescent silicon based devices [1–3]. The discovery of photoluminescence [1] in PS and the understanding of the growth of nanostructures [2] opened the field to a large amount of work on this material. For practical applications, the electroluminescence (EL) is the crucial point. The development of electroluminescent devices (ELD) in PS technology faces some specific problems. The material has a large internal surface; therefore, it shows a tendency to undergo a chemical change when it is exposed to air. Furthermore, nanoporous silicon shows a very low electrical conductivity which causes problems for the EL efficiency. However, ELD with wet contacts [4, 5] have proved to be efficient. This shows that, in principle, PS is a good material to get EL. Most of the ELD present a simple integrated structure of a porous layer and a contact layer on top. For contact, thin metals such as gold, indium tin oxide (ITO), silicon carbide, and conductive polymers are used. An advanced structure has p-n junction within the porous region. For this work, we propose to use a ZnO:In
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