Physical Properties of Nanostructured CdO Films from Alkaline Baths Containing Saccharin as Additive
Nanostructured cadmium oxide (CdO) films were fabricated on glass substrates from alkaline baths containing saccharin as an additive by a successive ionic layer adsorption and reaction (SILAR) method. The effects of saccharin concentration in the bath on the structural, morphological, and optical properties were studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence, and Raman spectroscopy. The analyses showed that the surface morphologies, XRD peak intensities, Raman spectroscopy, and photoluminescence properties of CdO films changed with saccharin concentration. From the results, it can be said that morphological characteristic and optical properties of the films could be calibrated by adding various saccharin percentages in the growth bath.
CTAB and acetic acid effect in the nanocrystallite growth of spray deposited CdO thin films
Abstract CdO thin films were deposited on glass substrates from cadmium acetate dihydrate along with precursor additives, acetic acid and CTAB using home built splay pyrolysis unit. XRD studies imply that the CdO thin films to be preferably oriented in the (1 1 1) plane. The Williamson–Hall plot indicates the presence of microstrain, especially high with acetic acid additive. Surface morphology was found to be closely packed spherical crystallite with precursor additives. Optical studies reveal a considerable change in the transmittance and band gap. Peak position is shifted in the Raman spectra, due to precursor additives.
Influence of the annealing and operating temperatures on the gas-sensing properties of rf sputtered WO3 thin-film sensors
Abstract The sensing properties of WO 3 thin films deposited by rf sputtering onto silicon substrates have been investigated. After deposition, the films underwent an annealing process in dry air that lasted 24 h. Three different annealing temperatures (350, 400 and 450 °C) were used to analyze the influence of this parameter on the sensor response. The morphology and composition of the films were studied by AFM and XPS. The films were found to be essentially inhomogeneous. The oxygen-to-tungsten atomic ratio of the active layers reveals that, irrespective to the annealing temperature used, the WO 3 active layers were close to their stoichiometric formulation, although a tendency to loose oxygen atoms at the higher annealing temperatures tested was inferred. The sensitivity of the films to ammonia, nitrogen dioxide, ethanol, benzene, methane and carbon monoxide was studied at three different operating temperatures (300, 350 and 370 °C). By selecting the appropriate annealing and operating temperatures, it was found possible to selectively detect nitrogen dioxide in the presence of ethanol and ammonia, or to detect ammonia in the presence of ethanol.