Maintaining a constant voltage the growth of titanium oxide (T iO 2 ) with a tubular geometry was studied. Therefore, the optimal parameters for the growth of TiO 2 were established using an organic electrolytic solution with a total volume of 150ml, composed of water/hydrofluoric acid/ammonium fluoride/ethylene glycol. The anodization conditions were varied, such as: time (60 -215 min), electric potential (5 -20 V), water content (0.0 -2.0 ml), and pH (4.8 -5.1). In this procedure, the conformation of long, open nanotubes with smooth walls was achieved, obtaining a maximum length of 1.90 µm for the nanotubes. However, in some samples before and after annealing a remnant layer can be seen that extends over some regions of the surface of the nanotubes. By means of the current density curves-time (J vs.t), we were able to specify the distinct growth zones of the nanotubes. The samples also were studied structurally by means of X-ray with thermal treatment (ambient−450 0 C). In addition, it was determined, via ultraviolet-visible (UV-Vis) spectroscopy, that the band gap energy varies (3.45 eV−3.03eV).
Here, we present electronic and transport properties of quaternary Cu2ZnSnSe4 (CZTSe) nanocrystalline films fabricated by physical co-evaporation. The samples were grown on soda-lime glass substrates and synthesis parameter ranges, Cu mass and substrate temperature were varied. Using thermopower at room temperature and spectral transmittance we found that the material is characterized by n-type conductivity and forbidden energy bandwidth of 1.7 eV, respectively. Electrical conductivity means (low temperature region; 90-200 K) showed that conductivity processes occur via variable range hopping between extended states. We obtained the parameters characterizing this mechanism, activation energy (Whopp), and range hopping (Rhopp), by employing the percolation theory and diffusion model. The density of defect states near the Fermi level of the material, N (EF) of the CZTSe samples is about 3,403x10 18 cm -3 eV -1 . We found a correlation between deposition parameters and electrical properties and observed a parameter influence on the formation of additional phases in the compound.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.