Thin films of tin oxide mixed cerium oxide were grown on unheated substrates by physical vapor deposition. The films were annealed in air at 500 °C for two hours, and were characterized using X-ray photoelectron spectroscopy, atomic force microscopy and optical spectrophotometry. X-ray photoelectron spectroscopy and atomic force microscopy results reveal that the films were highly porous and porosity of our films was found to be in the range of 11.6–21.7%. The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive. We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm. Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

Zinc nitride thin films were grown on fused silica substrates at 300 °C by radio frequency magnetron sputtering. Films were grown at different N2/Ar flow rate ratios of 0.20, 0.40, 0.60, 0.80, and 1.0. All the samples have grain-like surface morphology with an average surface roughness ranging from 4 to 5 nm and an average grain size ranging from 13 to16 nm. Zn3N2 samples grown at lower N2/Ar ratio are polycrystalline with secondary phases of ZnO present, whereas at higher N2/Ar ratio, no ZnO phases were found. Highly aligned films were achieved at N2/Ar ratio of 0.60. Hall effect measurements reveal that films are n-type semiconductors, and the highest carrier concentration and Hall mobility was achieved for the films grown at N2/Ar ratio of 0.60. X-ray photoelectron study was performed to confirm the formation of Zn–N bonds and to study the presence of different species in the film. Depth profile XPS analyses of the films reveal that there is less nitrogen in the bulk of the film compared to the nitrogen on the surface of the film whereas more oxygen is present in the bulk of the films possibly occupying the nitrogen vacancies.

Titanium nitride thin films were grown on Si(001) and fused silica substrates by radio frequency reactive magnetron sputtering. Post-growth annealing of the films was performed at different temperatures from 300 °C to 700 °C in nitrogen ambient. Films annealed at temperatures above 300 °C exhibit higher surface roughness, smaller grain size and better crystallinity compared to the as-grown film. Bandgap of the films decreased with the increase in the annealing temperature. Hall effect measurements revealed that all the films exhibit n-type conductivity and had high carrier concentration, which also increased slightly with the increase in the annealing temperature. A detailed depth profile study of the chemical composition of the film was performed by x-ray photoelectron spectroscopy confirming the formation of Ti-N bond and revealing the presence of chemisorbed oxygen in the films. Annealing in nitrogen ambient results in increased nitrogen vacancies and non-stoichiometric TiN films.

Scanning tunneling microscopy images confirm electron difraction studies that the zinc-blende $\mathrm{GaN}(001)\mathrm{\text{−}}4\times$ reconstruction consists of rows aligned along $[110]$ with a spacing along $[1\overline{1}0]$ of $4a$. Dual-bias imaging shows a 180° shift of the corrugation maximum position between the profiles of empty and occupied states, in agreement with surface simulations based on the $4\times 1$ linear tetramer model of Neugebauer et al. [ Phys. Rev. Lett. 80, 3097 (1998)]. Electronic structure calculations predict a surface band gap of 1.1 eV, close to the measured value of 1.14 eV and the previously predicted value (1.2 eV). Despite the successes of this model, high-resolution images reveal an unexpected $3\times$ periodicity (not seen in diffraction) along the $[110]$ row direction, indicating the need for a $4\times 3$ model, and putting into question the existence of linear Ga tetramers.