A study on the propane gas-sensing properties of Cu-doped ZnO thin films is presented in this work. The films were deposited on glass substrates by sol-gel and dip coating methods, using zinc acetate as a zinc precursor, copper acetate and copper chloride as precursors for doping. For higher sensitivity values, two film thickness values are controlled by the six and eight dippings, whereas for doping, three dippings were used, irrespective of the Cu precursor. The film structure was analyzed by X-ray diffractometry, and the analysis of the surface morphology and film composition was made through scanning electron microscopy (SEM) and secondary ion mass spectroscopy (SIMS), respectively. The sensing properties of Cu-doped ZnO thin films were then characterized in a propane atmosphere, C₃H₈, at different concentration levels and different operation temperatures of 100, 200 and 300 °C. Cu-doped ZnO films doped with copper chloride presented the highest sensitivity of approximately 6 × 10⁴, confirming a strong dependence on the dopant precursor type. The results obtained in this work show that the use of Cu as a dopant in ZnO films processed by sol-gel produces excellent catalysts for sensing C₃H₈ gas.

In this paper, we demonstrate that the sputtering of solids by ions of low (<30 keV) and even ultralow energies (<2 keV) is accompanied by nonlinear effects. These nonlinear effects are the result of heating a significant part of the cascades of collisions above the effective melting temperature of the material with the formation of local melts or “thermal spots” (a special case of the thermal spike regime). Nonlinear effects should primarily be observed in dense targets irradiated by heavy and cluster ions. In this paper, the question of the lifetime of such spots and their effect on the emission of secondary particles and the formation of specific surface topography is examined in detail. Another important assumption of the model is the existence of an intermediate ion sputtering regime, in that both linear cascades and thermal spots can exist simultaneously. A phenomenological model based on the effect of a rapid decrease in the cascade volume with a monotonic decrease in the energy of primary ions below 3 keV, which leads to the formation of thermal spots at ultralow energies (<2 keV), is also proposed. The suggested thermal spot model allows us to explain several experimental data that have not yet been explained in the framework of the traditional sputtering models. In particular, a simple explanation is given for the formation of pores in the surface layer during implantation and the formation of a relief on an ion-bombarded surface such as nanodots, pits (holes), and in the form of a foam-like surface. The small stationary concentration of cesium on the surface of the target sputtered by low-energy cesium ions is also explained.

The secondary ion mass-spectroscopy technique was used to study the results of hydration of borosilicate, aluminosilicate, and soda-lime silicate glasses in ¹H₂¹⁸O water vapor containing 97% of the isotope ¹⁸O. It is shown that hydration of the surface of the soda-lime silicate glass occurs as a result of the ion-exchange reaction with alkali metals. In the case of borosilicate and aluminosilicate glasses, water molecules decompose on the glass surface, with the observed formation of hydrogenated layer in the glass being the result of a solid-state chemical reaction—presumably, with the formation of hydroxides from aluminum and boron oxides.

This paper describes research focused on investigating the effect of hydrogen (H) atom insertion into the grain boundaries of polycrystalline diamond (PCD) films. This is required in order to understand the key morphological, chemical, physical, and electronic properties of the films. The PCD films were grown using the hot filament chemical vapor deposition (HFCVD) process, with flowing Ar gas mixed with CH₄ and H₂ gases to control film growth into microcrystalline diamond (MCD, 0.5–3 µm grain sizes), nanocrystalline diamond (NCD, 10–500 nm grain sizes), and ultrananocrystalline diamond (UNCD, 2–5 nm grain sizes) films depending on the Ar/CH₄/H₂ flow ratios. This study focused on measuring the H atom concentration of the PCD films to determine the effect on the properties indicated above. A simple model is presented, including a hypothesis that the two dangling bonds per unit cell of C atoms serve as the site of hydrogen incorporation. This correlates well with the observed concentration of H atoms in the films. Dangling bonds which are not passivated by hydrogen are postulated to form surface structures which include C double bonds. The Raman peak from these surface structures are the same as observed for transpolyacetyline (TPA). The data reveal that the concentration of H atoms at the grain boundaries is around 1.5 × 10¹⁵ atoms/cm² regardless of grain size. Electrical current measurements, using a conductive atomic force microscopy (CAFM) technique, were performed using an MCD film, showing that the current is concentrated at the grain boundaries. Ultraviolet photo electron spectroscopy (UPS) confirmed that all the PCD films exhibited a metallic behavior. This is to be expected if the nature of grain boundaries is the same regardless of grain size.

A new model of the depth-resolution function for secondary-ion mass spectrometry, which takes into account recoil implantation, ion mixing, and surface roughness formation under ion irradiation, is considered. A simple three-parameter equation is proposed to describe the depth-resolution function. Analytical expressions are obtained for two parameters.