3. Producción
Browse
4 results
Search Results
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Indirect excitation and luminescence activation of Tb doped indium tin oxide and its impact on the host's optical and electrical properties(IOP Publishing Ltd, 2022-05-26)The effect of adding terbium to indium tin oxide (ITO) thin films on the electrical, optical and light emission properties was investigated. The films were prepared by radio frequency dual magnetron sputtering, maintaining a high optical transmittance in the ultraviolet and visible spectral regions, and a low electrical resistivity ranging from 5 × 10 − 3 Ω ⋅ cm to 0.3 Ω ⋅ cm . Terbium-related luminescence is achieved after annealing at 470 ∘C in air at atmospheric pressure. Electrical resistivity and optical transmittance were measured after each annealing step to evaluate the compromise between the achieved light emission intensity, electrical and optical properties. Additionally, temperature dependence of Tb-related luminescence quenching was assessed by temperature-dependent photoluminescence measurements, from 83 to 533 K, under non-resonant excitation. Thermal quenching activation energies suggest an effective energy transfer mechanism from the ITO host to the rare-earth (RE) ions. This indirect excitation mechanism was modeled using a spherical potential-well and a tight-binding one-band approximation approaches, describing a short-range charge trapping process and subsequent formation of bound excitons to RE ion clusters. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Thickness dependence of the room-temperature ethanol sensor properties of Cu2O polycrystalline films(Institute of Physics, 2024-08-05)This study investigates the fabrication process of copper thin films via thermal evaporation, with precise control over film thickness achieved through Z-position adjustment. Analysis of the as-fabricated copper films reveals a discernible relationship between grain size (〈D〉) and Z-position, characterized by a phenomenological equation 〈 D 〉 XRD n ( Z ) = 〈 D 〉 0 n 1 + 3 2 r Z 2 + 15 8 r Z 4 , which is further supported by a growth exponent (n) of 0.41 obtained from the analysis. This value aligns well with findings in the literature concerning the growth of copper films, thus underlining the validity and reliability of our experimental outcomes. The resulting crystallites, ranging in size from 20 to 26 nm, exhibit a resistivity within the range of 3.3-4.6 μΩ · cm. Upon thermal annealing at 200 °C, cuprite Cu2O thin films are produced, demonstrating crystallite sizes ranging from ∼9 to ∼24 nm with increasing film thickness. The observed monotonic reduction in Cu2O crystallites relative to film thickness is attributed to a recrystallization process, indicating amorphization when oxygen atoms are introduced, followed by the nucleation and growth of newly formed copper oxide phase. Changes in the optical bandgap of the Cu2O films, ranging from 2.31 to 2.07 eV, are attributed mainly to the quantum confinement effect, particularly important in Cu2O with size close than the Bohr exciton diameter (5 nm) of the Cu2O. Additionally, correlations between refractive index and extinction coefficient with film thickness are observed, notably a linear relationship between refractive index and charge carrier density. Electrical measurements confirm the presence of a p-type semiconductor with carrier concentrations of ∼1014 cm−3, showing a slight decrease with film thickness. This phenomenon is likely attributed to escalating film roughness, which introduces supplementary scattering mechanisms for charge carriers, leading to a resistivity increase, especially as the roughness approaches or surpasses the mean free path of charge carriers (8.61 nm). Moreover, ab-initio calculations on the Cu2O crystalline phase to investigate the impact of hydrostatic strain on its electronic and optical properties was conducted. We believe that our findings provide crucial insights that support the elucidation of the experimental results. Notably, thinner cuprite films exhibit heightened sensitivity to ethanol gas at room temperature, indicating potential for highly responsive gas sensors, particularly for ethanol breath testing, with significant implications for portable device applications. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Impact of the thickness on the optical, electronic, and structural properties of sputtered Cu2S thin films(American Institute of Physics Inc., 2024-02-14)A successful hexagonal Cu 2 S p-type semiconductor thin film using DC magnetron sputtering is reported. Films with thickness gradients were deposited by taking advantage of deposition geometry and target dimensions. X-ray diffraction (XRD) analysis confirmed the exclusive formation of the hexagonal Cu 2 S phase. Elemental composition and thickness dependence with the sample position were determined using energy-dispersive x-ray spectroscopy. Optical properties, including the optical bandgap, refractive index, and extinction coefficient, were assessed by modeling transmittance spectra. The Tauc-Lorentz oscillator and Drude models were employed for this purpose. XRD data analysis successfully determined the film thickness ( t X R D ) as a function of the sample position, aligning well with thickness values ( t T ) derived from transmittance spectra analyses. These results were further supported by film thickness values ( t S E M ) obtained from cross-sectional SEM images. Charge carrier density and mobility, extracted from the optical models, were found to be consistent with DC electrical measurements. AC impedance curves were effectively modeled with RL-RC parallel circuits. The results indicate that the inductance (L) and capacitance (C) components of the films increase with decreasing film thickness. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Cu-Doped SnO₂ Nanocrystals: Tunable Magnetism, Critical Incorporation Limit, and Defect Configuration Analysis by EPR and Ab Initio DFT(American Chemical Society, 2025-11-05)Copper in oxide semiconductors exhibits distinct electronic and magnetic behavior depending on its oxidation state, with Cu¹⁺ acting as a nonmagnetic impurity and Cu²⁺ contributing to the magnetic moment. In SnO₂, Cu incorporation represents a heterovalent substitution for Sn⁴⁺, which inherently promotes formation of compensating defects, particularly oxygen vacancies, that can strongly influence electronic and magnetic properties. To elucidate these effects, we investigated Cu-doped SnO₂ nanocrystals through combined experimental and theoretical approaches. Electron paramagnetic resonance (EPR) revealed that Cu incorporation of up to 3% enhances resonance intensity, consistent with isolated Cu²⁺ ions in the SnO₂ matrix. Beyond 3%, the EPR signal intensity decreases, and hyperfine parameters stabilize due to Cu²⁺ clustering and spin–spin interaction. Magnetization measurements revealed a paramagnetic phase (reflecting the presence of isolated Cu²⁺) that coexists with a ferromagnetic phase attributed to bound magnetic polarons and magnetic clustering. Complementary first-principles calculations showed that Cu substitution modifies the electronic structure by introducing localized density of states variations and altering the spin–charge density distribution, particularly near oxygen vacancies. Deeper in-plane defects were found to stabilize magnetization, whereas surface defects promoted competing ferromagnetic and antiferromagnetic interactions. Structural characterization by X-ray diffraction and morphological analysis using high-resolution transmission electron microscopy further confirmed lattice compression and particle size reduction with increasing Cu-content. The calculated and experimental findings provide a comprehensive and interconnected understanding, not yet emphasized in the literature, of the interplay among defects, doping, and magnetism in Cu-doped SnO₂.1