- Dpto. Física de Materiales
Facultad de Ciencias Físicas - UCM
Ciudad Universitaria s/n
28040 - Madrid (Spain) - +34 91394 4790
P. Hidalgo
Universidad Complutense de Madrid, Fisica De Materiales, Faculty Member
ABSTRACT Indium germanate (In2Ge2O7) nanobelts and nano- and microwires have been synthesized by a thermal evaporation–deposition method and their luminescence properties have been investigated. High-resolution transmission electron... more
ABSTRACT Indium germanate (In2Ge2O7) nanobelts and nano- and microwires have been synthesized by a thermal evaporation–deposition method and their luminescence properties have been investigated. High-resolution transmission electron microscopy shows the growth direction of the nanobelts. Cathodoluminescence in the scanning electron microscope and photoluminescence show the existence of a broad complex emission band with several components in the range 1.70–2.80 eV and a band at 3.20–3.30 eV. Comparison of the observed luminescence with the luminescence of GeO2 suggests that some of the components are related to the presence of Ge2O7 groups in the germanate crystal structure and not to the sheets of InO6 octahedra of the structure. Waveguiding behaviour of In2Ge2O7 nano- and microwires has been demonstrated under excitation with 325 nm light. Raman spectra of the nanobelts have characteristic peaks which could enable to correlate specific Raman features with the presence of In2Ge2O7 and to use this technique for indium germanate assessment.
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Research Interests: Materials Science, Biomedical Engineering, Surface Roughness, Surface modification, Edge Detection, and 11 moreLeakage Current, Surface Morphology, Nuclear science, Surface treatment, Materials Processing, Gamma Ray, Surface Defects, Gamma-ray Spectroscopy, High energy, Cadmium Zinc Telluride, and Rough Surface
This paper describes the “pairing - dissociation” behaviour of metal-acceptor pairs and proposes a method to measure metal concentrations in p-type boron doped silicon based on a contactless measurement technique. The first part of this... more
This paper describes the “pairing - dissociation” behaviour of metal-acceptor pairs and proposes a method to measure metal concentrations in p-type boron doped silicon based on a contactless measurement technique. The first part of this paper sums up the previous non destructive electrical characterization methods that have led to the evaluation of iron concentrations in p-type boron- doped silicon by the inspired contactless techniques. It is demonstrated that the lifetime measurement method proposed allows the detection of contaminants at concentrations as low as 109at.cm-3. In the second part, the specific cases of iron and chromium that are among the most harmful metal contaminants are discussed. We show that these contaminants, even if their concentrations are not known, are identifiable by contactless measurements that allow the analysis of their kinetics of pairing with boron atoms and of their respective interactions with extended defects, such as grain boundaries in multicr...
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Cathodoluminescence (CL) in the scanning electron microscope (SEM) has been used to investigate the effect of doping with chromium and vanadium on the native accepters and on the general structure of extended defects of gallium antimonide... more
Cathodoluminescence (CL) in the scanning electron microscope (SEM) has been used to investigate the effect of doping with chromium and vanadium on the native accepters and on the general structure of extended defects of gallium antimonide single crystals. Both impurities cause the reduction of the CL band at 775 meV (band A) attributed to a native acceptor. This effect is explained by the formation of a complex involving the dopant. CL images reveal the presence of precipitates and inhomogeneities in impurity distribution.
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Bi doped ZnO nanowires and rods have been grown by a catalyst free evaporation-deposition method with precursors containing either ZnO and Bi2O3 or ZnS and Bi2O3 powders. The use of ZnS as a precursor was found to lead to a higher density... more
Bi doped ZnO nanowires and rods have been grown by a catalyst free evaporation-deposition method with precursors containing either ZnO and Bi2O3 or ZnS and Bi2O3 powders. The use of ZnS as a precursor was found to lead to a higher density of nano- and microstructures at lower temperatures than by using ZnO. Energy dispersive x-ray spectroscopy (EDS) shows that
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Binary semiconductor oxides, such as ZnO, SnO2, Ga2O3, have attracted high interest due to their specific optical and electrical properties. Most of them have applications as transparent conducting oxides and as gas sensors materials.... more
Binary semiconductor oxides, such as ZnO, SnO2, Ga2O3, have attracted high interest due to their specific optical and electrical properties. Most of them have applications as transparent conducting oxides and as gas sensors materials. Also, the synthesis and properties of ...
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Broad emission bands in semiconducting oxides due to native defects could readily be an efficient source of white light if they are adjusted properly. In this work, Zn2GeO4 nanoparticles of 10 and 16 nm sizes, obtained by a precipitation... more
Broad emission bands in semiconducting oxides due to native defects could readily be an efficient source of white light if they are adjusted properly. In this work, Zn2GeO4 nanoparticles of 10 and 16 nm sizes, obtained by a precipitation method, are presented as potential white light emitter. Temperature dependence measurements have been performed to discuss the Zn2GeO4 luminescence, which consist of emission bands in the ultraviolet, blue and green regions. The analysis of these results provided some clues about the interplay between defect-related centres and the surface states in nanocrystalline Zn2GeO4. Finally, a highly efficient cold-white emission at room temperature has been achieved from this nanomaterial.
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Cathodoluminescence (CL) in the scanning electron microscope (SEM) has been used to investigate the effect of doping with an isoelectronic dopant, aluminum, on the native acceptors and on the general structure of extended defects of... more
Cathodoluminescence (CL) in the scanning electron microscope (SEM) has been used to investigate the effect of doping with an isoelectronic dopant, aluminum, on the native acceptors and on the general structure of extended defects of gallium antimonide single crystals. While there is no significant change in the native defect content, decoration of non-radiative recombination centers or extended defects occurs as a result of aluminum doping.
ABSTRACT The defect structure of Te-doped GaSb samples co-doped with Er2O3 and grown by the vertical Bridgman technique has been analysed. This study was carried out for different Er and Te concentrations. The defect structure of the... more
ABSTRACT The defect structure of Te-doped GaSb samples co-doped with Er2O3 and grown by the vertical Bridgman technique has been analysed. This study was carried out for different Er and Te concentrations. The defect structure of the samples has been analysed by means of cathodoluminescence (CL), scanning electron microscopy (SEM) and wavelength dispersive X-ray microanalysis (WDX). The effect of the defect structure and sample composition on the electrical properties of the material has been established taking into account the results obtained by means of the van der Pauw technique.
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By means of a contactless microwave phase shift technique, the minority carrier lifetime and surface recombination velocity were measured in multicrystalline silicon wafers containing iron and chromium. The bulk lifetime can be deduced,... more
By means of a contactless microwave phase shift technique, the minority carrier lifetime and surface recombination velocity were measured in multicrystalline silicon wafers containing iron and chromium. The bulk lifetime can be deduced, leading to the determination of the concentration of interstitial iron [Fei ] associated with boron, after pair dissociation annealing at 210 °C. It is found that [Fei
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The cathodoluminescence (CL) technique is used to analyse the radiative recombination properties of four distinct silicon carbide (SiC) samples: a 6H-SiC n+-type Lely wafer, two off-axis 4H-SiC epitaxial layers of n type and p type, and a... more
The cathodoluminescence (CL) technique is used to analyse the radiative recombination properties of four distinct silicon carbide (SiC) samples: a 6H-SiC n+-type Lely wafer, two off-axis 4H-SiC epitaxial layers of n type and p type, and a (11\bar 20 )-oriented 4H-SiC n+-type substrate. The CL spectra, recorded at various temperatures and at various excitation conditions, show strong differences between the
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The luminescence of Te-doped GaSb crystals codoped with Er2O3 has been studied by means of cathodoluminescence (CL) using a scanning electron microscope. Doping with erbium oxide causes a substantial increase of the luminescence intensity... more
The luminescence of Te-doped GaSb crystals codoped with Er2O3 has been studied by means of cathodoluminescence (CL) using a scanning electron microscope. Doping with erbium oxide causes a substantial increase of the luminescence intensity of the crystals and spectral broadening. Deconvolution of the CL spectra reveals the existence of four components. The presence of erbium oxide induces a decrease of the 746 meV emission characteristic of Te-doped samples. CL images show a complex distribution of recombination centres which depends to a large extent on the local Te concentration.