A comparative analysis was performed of fluorine-doped tin oxide (FTO) thin films deposited through two different systems: pneumatic spray pyrolysis and ultrasonic spray pyrolysis. The films were deposited on glass substrates at 460 °C, with varying weight ratios of fluorine to tin (F/Sn = 0.35, F/Sn = 0.50, and F/Sn = 0.65). The investigation focuses on the evolution of the film’s crystallinity, structural, morphological, transmittance, optical, and electrical properties. Resonant nuclear reaction (RNR) and energy dispersive spectroscopy (EDS) techniques were used to confirm the presence of fluorine in the FTO samples. The results show that the sample with F/Sn = 0.50 deposited through pneumatic spray pyrolysis, with a figure of merit of 34.5 × 10⁻³ Ω⁻¹, exhibits the best characteristics for use as electrodes in optoelectronic devices, particularly in the fabrication of solar cells.

This work is focused on making a correlation between results obtained by using spectroscopy and microscopy techniques from single and twofold-layer Silicon-Rich Oxide (SRO) films. SRO films single-layer and twofold-layer characterizations were compared considering the conditions as-grown and with thermal treatment at 1100 °C for 60 min in a nitrogen atmosphere. The thickness of the single-layer film is 324.7 nm while for the twofold-layer film it is 613.2 nm; after heat-treated, both thicknesses decreased until 28.8 nm. X-ray Photoelectron Spectroscopy shows changes in the excess-silicon in single-layer SRO films, with 10% in as-grown films and decreases to 5% for the heat-treated films. Fourier Transform Infrared Spectroscopy (FTIR) exhibits three characteristic vibrational modes of SiO₂, as well as, the vibrating modes associated with the Si-H bonds, which disappear after the heat treatment. With UV–Vis spectroscopy results we obtained the absorbance and the absorption coefficient for the SRO films in order to calculate the optical bandgap energy (Eg_opt), which increased with heat-treatment. The energy peaks of the photoluminescence spectra were used to calculate the silicon nanocrystal size, obtaining thus an average size of 1.89 ± 0.32 nm for the as-grown layer, decreasing the size to 1.64 ± 0.01 nm with the thermal treatment. On the other hand, scanning electron microscopy and high-resolution transmission electron microscopy images confirm the thickness of the twofold-layer SRO films as 628 nm for the as-grown layer and 540 nm for the layer with heat-treatment, and the silicon nanocrystal size of 2.3 ± 0.6 nm for the films with thermal treatment.

In this work, electroluminescence in Metal-Insulator-Semiconductors (MIS) and Metal-Insulator-Metal (MIM)-type structures was studied. These structures were fabricated with single- and double-layer silicon-rich-oxide (SRO) films by means of Hot Filament Chemical Vapor Deposition (HFCVD), gold and indium tin oxide (ITO) were used on silicon and quartz substrates as a back and front contact, respectively. The thickness, refractive indices, and excess silicon of the SRO films were analyzed. The behavior of the MIS and MIM-type structures and the effects of the pristine current-voltage (I-V) curves with high and low conduction states are presented. The structures exhibit different conduction mechanisms as the Ohmic, Poole–Frenkel, Fowler–Nordheim, and Hopping that contribute to carrier transport in the SRO films. These conduction mechanisms are related to the electroluminescence spectra obtained from the MIS and MIM-like structures with SRO films. The electroluminescence present in these structures has shown bright dots in the low current of 36 uA with a voltage of −20 V to −50 V. However, when applied voltages greater than −67 V with 270 uA, a full area with uniform blue light emission is shown.

En este trabajo se aplica el modelo de cuatro fases, definición de producto, diseño conceptual, diseño de materialización y diseño a detalle para la construcción de una fresadora CNC (control numérico por computadora) para el maquinado de piezas en fibra de densidad media (MDF) de 2.5-12mm de espesor, el trabajo contribuye a mostrar la aplicación metodológica establecida por Pahl & Beitz en un ejemplo real de diseño en ingeniería. La fresadora CNC se construye con una estructura de aluminio de 20×40mm y 20×20mm, así como MDF de 12mm de espesor que brinda la posibilidad de maquinar modelos a partir de diseños CAD en 2D y 3D, el espacio de trabajo efectivo (x, y, z) es de 270×270×50mm. El maquinado de piezas se realiza a partir del movimiento traslacional que realiza el sistema de movimiento de la fresadora sobre el plano x-y y la altura definida sobre el eje z, así como del movimiento rotacional del husillo del sistema de corte. Se presentan las vistas isométricas del diseño CAD de los sistemas de movimiento sobre los ejes x, y, z y de la mesa de maquinado. El control de la fresadora CNC se realiza mediante una tarjeta Arduino uno, una placa CNC shield para Arduino, controladores para motor a pasos, motores a paso de 1.8°. Todos los componentes son comerciales, lo que permite desarrollar un prototipo de bajo costo. Finalmente, se describe el proceso de operación de la máquina, así como la hoja de proceso para el maquinado de piezas.