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Libu Manjakkal, I. Packia Selvam, S.N. Potty and R.S. Shinde
Aluminium-doped zinc oxide thin films exhibit interesting optoelectronic properties, which make them suitable for fabrication of photovoltaic cell, flat panel display…
Aluminium-doped zinc oxide thin films exhibit interesting optoelectronic properties, which make them suitable for fabrication of photovoltaic cell, flat panel display electrode, etc. It has been shown that aluminium dopant concentration and annealing treatment in reduced atmosphere are the major factors affecting the electrical and optical properties of aluminium doped zinc oxide (AZO) film. Here, the authors report the structural, optical and electrical properties of aluminium-doped zinc oxide thin films fabricated by dip coating technique and annealed in air atmosphere, thereby avoiding hazardous environments such as hydrogen. The aim of this paper was to systematically investigate the effect of annealing temperature on the electrical properties of dip-coated film.
Aluminium-doped ZnO thin films were prepared on corning substrates by dip coating method. Aluminium concentration in the film varied from 0.8 to 1.4 mol per cent. Films have been characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, UV-visible spectroscopy and Hall measurements. The deposited films were heat treated at 450-600°C, in steps of 50°C for 1 h in air to study the improvement in electrical properties. Films were also prepared by annealing at 600°C in air for durations of 1, 2, 4 and 6 h. Envelope method was used to calculate the variation of the refractive index and extinction coefficient with wavelength.
The electrical resistivity is found to decrease considerably when the annealing time is increased from 1 to 4 h. The films exhibited high transmittance (>90 per cent) in the visible range, and the optical band gaps were found to change as per the Moss–Burstien effect, and this was consistent with the observed changes in the carrier concentration.
The study shows the effect of annealing in air, avoiding hazardous reduced environment, such as hydrogen, to study the improvement in electrical and optical properties of aluminum-doped zinc oxide films. Envelope method was used to calculate the variation of optical constants with wavelength.
Katarina Cvejin, Libu Manjakkal, Jan Kulawik, Krzysztof Zaraska and Dorota Szwagierczak
– This paper aims to investigate different properties of synthesized perovskite Sm0.9Sr0.1CoO3-δ and its potential for application in potentiometric oxygen sensors.
This paper aims to investigate different properties of synthesized perovskite Sm0.9Sr0.1CoO3-δ and its potential for application in potentiometric oxygen sensors.
The powder was obtained through solid-state reaction method and characterized by thermogravimetric/differential thermal analyzer and X-ray diffraction. It was used for both making a paste and pressing into rods for sintering. The prepared paste was deposited on alumina and yttria-stabilized zirconia substrates, by screen printing. Thick film conductivity, bulk conductivity and Seebeck coefficient of sintered rods were measured as a function of temperature. An oxygen concentration cell was fabricated with the screen-printed perovskite material as electrodes.
Electrical conductivity of the bulk sample and thick film increases with the increase in temperature, showing semiconductor-like behavior, which is also indicated by relatively high values of the measured Seebeck coefficient. Estimated values of the activation energy for conduction are found to be of the same magnitude as those reported in the literature for similar composition. An investigation of Nernstian behavior of the fabricated cell confirmed that Sm0.9Sr0.1CoO3-δ is a promising material for application in oxygen potentiometric sensors.
Gas sensor research is focused on the development of new sensitive materials. Although there is scarce information on SmCoO3-δ in the literature, it is mostly investigated for fuel cell applications. Results of this study imply that Sr-doped SmCoO3-δ is a good candidate material for oxygen potentiometric sensor.