Er-doped TiO2−xNx films were grown by Ar+ ion-beam sputtering a Ti + Er target under different N2 + O2 high-purity atmospheres. The compositional-structural properties of the samples were investigated after thermal annealing the films up to 1000 °C under a flow of oxygen. Sample characterization included x-ray photoelectron spectroscopy, grazing incidence x-ray diffraction, Raman scattering, and photoluminescence experiments. According to the experimental data, both composition and atomic structure of the samples were very sensitive to the growth conditions and annealing temperature. In the as-deposited form, the N-rich TiO2−xNx films presented TiN crystallites and no photoluminescence. As the thermal treatments proceed, the films were transformed into TiO2 and Er3+-related light emission were observed in the visible and near-infrared ranges at room-temperature. Whereas the development of TiO2 occurred due to the insertion-diffusion of oxygen in the films, light emission originated because of optical bandgap widening and/or structural-chemical variations in the vicinity of the Er3+ ions. Finally, the photoluminescence results in the visible range suggested the potential of the present samples in producing an optically based temperature sensor in the ∼150–500 K range.
This study reports on the properties of nitrogen doped titanium dioxide (TiO 2 ) thin films considering the application as transparent conducting oxide (TCO). Sets of thin films were prepared by sputtering a titanium target under oxygen atmosphere on a quartz substrate at 400 or 500°C. Films were then doped at the same temperature by 150 eV nitrogen ions. The films were prepared in Anatase phase which was maintained after doping. Up to 30at% nitrogen concentration was obtained at the surface, as determined by in situ x-ray photoelectron spectroscopy (XPS). Such high nitrogen concentration at the surface lead to nitrogen diffusion into the bulk which reached about 25 nm. Hall measurements indicate that average carrier density reached over 10 19 cm -3 with mobility in the range of 0.1 to 1 cm 2 V -1 s -1 . Resistivity about 3.10 -1 cm could be obtained with 85% light transmission at 550 nm. These results indicate that low energy implantation is an effective technique for TiO 2 doping that allows an accurate control of the doping process independently from the TiO 2 preparation. Moreover, this doping route seems promising to attain high doping levels without significantly affecting the film structure. Such approach could be relevant for preparation of N:TiO 2 transparent conduction electrodes (TCE). Graphical abstractHighlights A two-step process for preparation of N:TiO 2 transparent conductor is proposed. Low energy nitrogen ions are used after Anatase thin film deposition. Approach allows excellent control of crystal, optical and electronic properties. Resistivity as low as 3.10 -1 cm while transparency at 550nm is about 85%.
Lead iodide (PbI2) is a precursor for the preparation of the organolead iodide perovskite (CH3NH3PbI3), which has been used in the fabrication of highly efficient solar cells. In this work, a novel route for the deposition of PbI2 thin films is performed by rf sputtering a target made from compressed PbI2 powder. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) revealed that the PbI2 films produced were uniform, pinhole-free, polycrystalline, and had low roughness. A small concentration of Pb nanocrystals observed within the films is attributed to differences in the sputtering yield of lead and iodide from the PbI2 target. A dependence of band gap on rf sputtering power was observed, which was associated with a reduction in the concentration of Pb nanocrystals. The PbI2 films were efficiently converted into CH3NH3PbI3 perovskite films through the immersion into a methylammonium iodide (MAI) solution, which also converted the remaining Pb nanocrystals into perovskite. This methodology has the potential to forge the way toward a new method for the fabrication of large-area perovskite solar cells.
Bismuth triiodide (BiI 3 ) has been studied in recent years with the aim of developing lead-free semiconductors for photovoltaics. It has also appeared in X-ray detectors due to the high density of the Bismuth element. This material is attractive as an active layer in solar cells, or may be feasible for conversion into perovskite-like material (MA 3 Bi 2 I 9 ), being also suitable for photovoltaic applications. In this study, we report on the thermomechanical properties (stress, hardness, coefficient of thermal expansion, and biaxial and reduced Young’s moduli) of BiI 3 thin films deposited by thermal evaporation. The stress was determined as a function of temperature, adopting the thermally induced bending technique, which allowed us to extract the coefficient of thermal expansion (31 × 10 −6 °C −1 ) and Young’s biaxial modulus (19.6 GPa) for the films. Nanohardness (~0.76 GPa) and a reduced Young’s modulus of 27.1 GPa were determined through nanoindentation measurements.
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.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.