A5050457251- ZnO doping and properties
- Electronic and Structural Properties of Oxides
- Electron and X-Ray Spectroscopy Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Gas Sensing Nanomaterials and Sensors
- Surface and Thin Film Phenomena
- Magnetic and transport properties of perovskites and related materials
- Ga2O3 and related materials
- Magnetic properties of thin films
- Copper-based nanomaterials and applications
- Advanced Condensed Matter Physics
- Semiconductor materials and devices
- Advanced Memory and Neural Computing
- Transition Metal Oxide Nanomaterials
- Magnetic Properties and Synthesis of Ferrites
- Ion-surface interactions and analysis
- Surface Roughness and Optical Measurements
- Quantum and electron transport phenomena
- Quantum Dots Synthesis And Properties
- nanoparticles nucleation surface interactions
- Advancements in Photolithography Techniques
- Advanced Materials Characterization Techniques
- Ferroelectric and Piezoelectric Materials
- Multiferroics and related materials
- Thermography and Photoacoustic Techniques
National University of Tucumán
2010-2020
Consejo Nacional de Investigaciones Científicas y Técnicas
2018-2020
Fundación Ciencias Exactas y Naturales
2014
Micron (United States)
2009
This work probes the relevance of oxygen vacancies in formation local ferromagnetic coupling between Fe ions at octahedral sites zinc ferrites. gives rise to a ferrimagnetic ordering with Curie temperatures above room temperature an otherwise antiferromagnetic compound. conclusion is based on experimental results from x-ray magnetic circular dichroism measurements $\mathrm{Fe}{\mathrm{L}}_{2,3}$ edges and magnetization performed ferrites, nanoparticles, films, different cation distributions...
Nonvolatile, electric-pulse-induced resistance switching is reported on S and Co doped ZnO thin films deposited different substrates using magnetron sputtering laser ablation. Two states were obtained by applying voltage pulses of polarity. The was observed regardless the substrate, dopant species, or microstructure samples. In samples, two are remarkably stable uniform.
X-ray absorption near-edge and grazing incidence x-ray fluorescence spectroscopy are employed to investigate the electronic structure of ZnFe${}_{2}$O${}_{4}$ thin films. The techniques used determine nonequilibrium cation site occupancy as a function depth oxygen pressure during deposition its effects on magnetic properties. It is found that low pressures below 10${}^{\ensuremath{-}3}$ mbar cause iron superoccupation tetrahedral sites without Zn${}^{2+}$ inversion, resulting in an ordered...
We report the existence of magnetic order at room temperature in Li-doped ZnO microwires after low energy H+ implantation. The with diameters between 0.3 and 10 μm were prepared by a carbothermal process. combine spectroscopy techniques to elucidate influence electronic structure local environment Zn, O, Li their vacancies on response. Ferromagnetism is obtained only implanting ZnO. overall results indicate that low-energy proton implantation an effective method produce necessary amount...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation M. Villafuerte, J. Ferreyra, C. Zapata, Barzola-Quiquia, F. Iikawa, P. Esquinazi, S. Heluani, de Lima, A. Cantarero; Defect spectroscopy of single ZnO microwires. Journal Applied Physics 7 April 2014; 115 (13): 133101. https://doi.org/10.1063/1.4869555 Download citation file: Ris (Zotero) Reference Manager...
Photoresistivity and its spectral response has been systematically studied in oxygen-deficient ${\mathrm{SrTiO}}_{3}$ single crystals for a wide range of resistivities $\ensuremath{\rho}$ carrier densities $n$. At room temperature we found persistent photoresistance that gradually decreases as is diminished or $n$ increased, addition to relaxation times seconds few minutes, suggesting trapping carriers playing major role. An analysis the excitation spectra showed two distinctive features are...
Photoconductance spectroscopy has been studied in epitaxial ZnO thin films with different thicknesses that range between 136 and 21 nm. We report a systematic decrease photoconductivity red shift band edge photoconductance spectra when the thickness is reduced. For thinner films, it found effective energy gap value diminishes. By time dependent measurements, we an enhanced contribution of slow relaxation times for thicker films. These effects are interpreted terms band-bending where...
The sub-band-gap excited photoconductivity (PC) time decay and the film structure of rf-sputter deposited nanocrystalline TiO2 thin films have been studied. Atomic force microscopy x-ray diffraction measurements were used to assess roughness, crystalline mean grain size films. Samples fabricated under different deposition conditions exhibit microstructures absolute PC, but similar persistent PC behaviour after switching off light source. very slow can be well represented by a function that...
We have measured the temperature dependence (30 K≤T≤300 K) of electrical resistance ZnO single crystals prepared by hydrothermal method in darkness and under influence light ultraviolet range. The decreases several orders magnitude at temperatures T<200 K after illumination. Electron paramagnetic resonance studies illumination reveal that excitation Li acceptor impurities is origin for giant negative photoresistance effect. Permanent effect also observed, which remains many hours...
Magnetic field dependent photoresistivity was measured at 280 K in ZnO ferromagnetic films grown on r-plane Al2O3 under a N2 atmosphere. A correlation between the negative magneto and existence of defect-induced magnetic order found. The effect transient is to slow down recombination process enhancing photocarriers density. experimental results demonstrate possibility tuning life time using diluted semiconductors.
The magneto-transport properties of single proton-implanted ZnO and Li(7%)-doped microwires have been studied. as-grown were highly insulating not magnetic. After proton implantation the Li(7%) doped showed a non-monotonous behavior negative magneto-resistance (MR) at temperature above 150 K. This is in contrast to monotonous NMR observed below 50 K for ZnO. difference transport wires related amount stable Zn vacancies created near surface region by Li doping. magnetic field dependence...
We have studied the correlation between photoconductivity and dark resistivity of single ZnO microwires. found that as-grown microwires with higher resistivities photoconductivities. However, when are thermal treated in vacuum, this is inverted. also analyzed behavior on protonated samples. discuss origin these behaviors terms interplay oxygen zinc vacancies their complexes acting as recombination or trapping centers.
By the use of invariance principles a procedure to characterize thin films using an electron microprobe is reported. Experimental quantities such as detected intensities and fluxes in boundaries solid system are described by invariant embedding method. In addition, differential equations given for probabilities different “destinations” electrons inside functions sample thickness. The reported here makes it possible perform microanalysis without need making approaches estimate ionization...
Electronic transport properties of twin roller melt spun ${\text{Cu}}_{100\ensuremath{-}x}{\text{Co}}_{x}$ $(x=10,15)$ alloys, are investigated in the temperature range between 10 and 300 K. Negative magnetoresistance is observed up to 0.85 T as-cast state, which further increases with a treatment 1 h at 923 Resistance exhibits metallic behavior below room draws minimum near 30 K all microstructures; this diminishes when magnetic field applied completely disappears after high-temperature...
The detection of defect‐induced magnetic order in single low‐dimensional oxide structures is general difficult because the relatively small yield magnetically ordered regions. In this work, effect an external field on transient photocurrent measured after light irradiation different ZnO samples at room temperature studied. It has been found that a produces change relaxation rate only samples. This can decrease or increase with field, depending whether region bulk surface sample. phenomenon...