Thin Tin Oxide Layer Research Articles

Analysis of the Energy Band Gap of Tin Oxide Thin Layers as Semiconductor Base Materials in Electronic Devices

The purpose of this study is to analyze the quality of optical properties such as energy band gap of thin layer of tin oxide doped with aluminum, tin oxide doped with fluorine, tin oxide doped with indium, tin oxide doped with aluminum-fluorine, tin oxide doped with aluminum-indium, and tin oxide doped with aluminum-fluorine-indium. The thin layer was synthesized using the sol-gel spin coating method. The ratio of basic ingredients and doping used in this study was 95:5% and 85:15%. The thin layer that has been formed is then heated at a temperature of 100 and 200 0C. The results of the analysis of optical properties showed that the largest values of direct and indirect energy band gap are in a thin layer of tin oxide doped with indium at a percentage of 95:5% for a temperature of 100 0C, namely 3.62 and 3.92 eV. The lowest values of direct and indirect energy band gap are in a thin layer of tin oxide doped with aluminum-fluorine-indium at a percentage of 85:15% for a temperature of 200 0C, namely 3.36 and 3.51 eV. These results indicate that the resulting energy band gap decreases with increasing doping concentration and sintering temperature. Based on the optical properties obtained, the thin layer can be used as the basic material for semiconductors in electronic devices.

Synthesis of SnO2 Thin Layer with a Doping Fluorine by Sol-Gel Spin Coating Method

A thin layer of tin oxide with doping Fluorine was synthesized using the sol-gel spin coating method. The synthesis aims to determine the quality of thin layers formed based on temperature variations and the number of layers. The basic material used is SnCl2.2H2O, while the doping material used is NH4F with variations in concentrations of dopants 0, 5, 10, 15, 20 and 25%. The substrate used is glass with a size of 10 x 10 x 3 mm. The synthesis of the thin layer includes substrate preparation, sol-gel making, thin film making, and heating process. At this stage SnO2:F is deposited on a glass substrate with sol-gel spin coating technique at the concentration of sol 1 M with doping levels of Fluorine 0, 5, 10, 15, 20 and 25%, and treated with maturation for 24 hours. Making a thin layer using a spin coater at a speed of 2000 rpm for 3 minutes. The layer made consists of one layer, two layers, three layers and four layers. The resulting layer shows that the higher the doping percentage, the higher the transparency of the layer. In addition, the more the number of layers, the lower the transparency level. Keywords: Thin Film, Tin Oxide, Fluorine, Sol-gel, Spin Coating

Metallic tin recovery from wave solder dross

Lead-free solders used in electronic components are predominately composed of alloys rich in tin. Significant quantities of partially oxidized tin alloy are generated during typical processing operations. The scrap has generally been considered to be tin oxide and suitable for recovery using electrolysis or reduction with charcoal and fuel oil at temperatures above 1000°C. This experimental work examines alternative processes for the recovery of metallic tin from this scrap. Microstructural and chemical characterisation of the scrap revealed that metallic tin was the predominant phase and was surrounded by a cover layer of tin oxide ranging in thickness from a few μm (micrometres) to 100μm. It was shown that even the thin layer of tin oxide prevented the coalescence of the metallic tin and inhibited recovery. It was concluded that removal of the oxide layer is the key step required in recovering the metal. The removal of the tin oxide was attempted using mechanical attrition (grinding in a ball mill) and chemical dissolution of the tin oxide layer by means of hydrochloric acid (HCl). The results of attrition in a ball mill indicated that the tin oxide covering layer was effectively reduced from the material over 53μm and the removed oxide was concentrated in particles less than this size. Furthermore, the remaining tin oxide layer can be almost completely removed by an acidic treatment with 2M HCl at room temperature and agitation for 30min. A flow sheet for the recovery of the metallic tin is presented below based on the obtained experimental results.

Hybrid nanocomposite based on cellulose and tin oxide: growth, structure, tensile and electrical characteristics

A highly flexible nanocomposite was developed by coating a regenerated cellulose film with a thin layer of tin oxide (SnO2) by liquid-phase deposition. Tin oxide was crystallized in solution and formed nanocrystal coatings on regenerated cellulose. The nanocrystalline layers did not exfoliate from cellulose. Transmission electron microscopy and energy dispersive x-ray spectroscopy suggest that SnO2 was not only deposited over the cellulose surface, but also nucleated and grew inside the cellulose film. Current–voltage characteristics of the nanocomposite revealed that its electrical resistivity decreases with deposition time, with the lowest value obtained for 24 h of deposition. The cellulose–SnO2 hybrid nanocomposite can be used for biodegradable and disposable chemical, humidity and biosensors.

Cathodoluminescence degradation of Y2SiO5:Ce thin films

Cathodoluminescence (CL) intensity of cerium-doped yttrium silicate (Y2SiO5:Ce) phosphor thin films grown by pulsed laser deposition were investigated for possible application in low voltage field emission displays (FEDs). A thin layer of tin oxide (SnO2) was ablated on some of the films in order to investigate the effect of the coated layer on the degradation of the CL intensity. Auger electron spectroscopy (AES) and CL spectroscopy were used to monitor changes in the surface chemical composition and luminous efficiency of the thin films. AES and CL spectroscopy were done with 2keV energy electrons and with beam current densities of 26 and 52mAcm−2. Measurements were done in high vacuum and in oxygen pressures of 1×10−8, 1×10−7, and 1×10−6Torr. Residual gas mass analysis showed that the adventitious carbon (C) was removed from the surface as volatile gas species, which is consistent with the electron stimulated surface chemical reaction model. The SnO2 coated thin films resulted in a lower but more stable CL intensity than the uncoated thin films. The degradation of the CL intensity was much less for the thin films after the same time period than for the Y2SiO5:Ce powders.

Low-resistance gas sensors fabricated from multiwalled carbon nanotubes coated with a thin tin oxide layer

Gas sensors have been fabricated from multiwalled carbon nanotubes (MWNTs) coated with a thin tin oxide layer, and have been used to detect oxidizing and reducing gases down to a ppm level. The barriers between the tin oxide nanocrystal grains on the MWNTs dominate the sensor resistance in different gases, and the conducting carriers in the MWNTs have a low resistance, which make the resistance of the sensors much lower than that of SnO2 nanobelt sensors. The resistance is 130kΩ in air, 230kΩ in 2ppm NO2, and 2.8MΩ in 50ppm NO2, so that impedance matching with amplifying circuits can be easily achieved.

Stability of the inner polyaniline solid contact layer in all-solid-state K+-selective electrodes based on plasticized poly(vinyl chloride).

A simple and powerful method based on UV-visible spectroscopy is presented for studying the stability of the inner electrically conducting polyaniline (PANI) solid contact (SC) layer in all-solid-state ion-selective electrodes (ISE). The influence of the plasticized poly(vinyl chloride) (PVC) membrane (ISM) composition and the pH of the sample solution on the stability of the solid contact is reported. PANI is used as a model compound in this study, but the method presented is universal and can be applied to different types and combinations of SCs and ISMs. It provides a tool for finding the best combination of conducting polymer and ISM for solid contact ISEs. PANI is deposited electrochemically either on glassy carbon or quartz glass covered with a thin layer of tin oxide, and a K+-selective ISM is deposited on top of the PANI layer. The short-term stability of the inner PANI layer is good for all membrane types in buffer solutions with pH 2, 6, and 9, indicating that the outer plasticized PVC membrane hinders the emeraldine salt-emeraldine base transition of the highly pH sensitive PANI layer. The solid contact K+-selective electrodes studied showed a Nernstian response of 58.2 +/- 0.1 mV/log aK. Significant differences are observed in the long-term stability of the inner PANI layer between the different membrane types. This indicates that water uptake of the PVC membrane and its permeability to OH- ions are critical parameters affecting the stability of the PANI layer. The solid contact electrodes based on PANI may require a composition of the PVC membrane different from those typically used in conventional ISEs with an inner solution.