Gas sensitive structures made of nanowires exhibit extremally large specific surface area, and a great number of chemically active centres that can react with the ambient atmosphere. This makes the use of nanomaterials promising for super sensitive gas sensor applications. Monoclinic β-Ga₂O₃ nanowires (NWs) were synthesized from metallic gallium at atmospheric pressure in the presence of nitrogen and water vapor. The nanowires were grown directly on interdigitated gold electrodes screen printed on Al₂O₃ substrates, which constituted the gas sensor structure. The observations made with transmission electron microscope (TEM) have shown that the nanowires are monocrystalline and their diameters vary from 80 to 300 nm with the average value of approximately 170 nm. Au droplets were found to be anchored at the tips of the nanowires which may indicate that the nanowires followed the Vapor–Liquid–Solid (VLS) mechanism of growth. The conductivity of β-Ga₂O₃ NWs increases in the presence of volatile organic compounds (VOC) even in the temperature below 600 °C. The gas sensor based on the synthesized β-Ga₂O₃ NWs shows peak sensitivity to 100 ppm of ethanol of 75.1 at 760 °C, while peak sensitivity to 100 ppm of acetone is 27.5 at 690 °C.

The photoreflectance spectra for heavily dopedp‐type GaAs/SI‐GaAs structures have been measured at room temperature for the energies in the vicinity of the GaAsband gap. The complex photoreflectance function is defined and determined by means of a Kramers–Krönig analysis from the measured photoreflectance spectra. The modulus of the complex photoreflectance function gives us the critical point energy whereas the phase of this function can be used for a topographical study of the homogeneity of the internal electric field in the structure.

This paper presents an analysis of thermal oxidation kinetics for Aluminium nitride (AlN) epitaxy layers using three methods: dry, wet and mixed. The structures thus obtained were examined by means of scanning electron microscope, energy-dispersive X-ray spectroscopy, spectroscopic ellipsometry and secondary ions mass spectroscopy. On the basis of the investigation results, a model of layer structure after oxidation was proposed, the thickness of the layers was assessed and the refractive indices for particular layers were determined. The modelling results prove that AlN thermal oxidation in dry oxygen follows the logarithmic law, wet oxidation follows the parabolic law, whereas mixed oxidation follows the linear law.