Al-doped NiO (NiO:Al) has attracted the interest of researchers due to its excellent optical and ... more Al-doped NiO (NiO:Al) has attracted the interest of researchers due to its excellent optical and electrical properties. In this work, NiO:Al films were deposited on glass substrates by the radio frequencies (rf) sputtering technique at room temperature and they were tested against ozone gas. The Oxygen content in (Ar-O2) plasma was varied from 2% to 4% in order to examine its effect on the gas sensing performance of the films. The thickness of the films was between 160.3 nm and 167.5 nm, while the Al content was found to be between 5.3 at% and 6.7 at%, depending on the oxygen content in plasma. It was found that NiO:Al films grown with 4% O2 in plasma were able to detect 60 ppb of ozone with a sensitivity of 3.18% at room temperature, while the detection limit was further decreased to 10 ppb, with a sensitivity of 2.54%, at 80 °C, which was the optimum operating temperature for these films. In addition, the films prepared in 4% O2 in plasma had lower response and recovery time compa...
The increasing air pollution taking place in virtue of human activity has a novel impact in our h... more The increasing air pollution taking place in virtue of human activity has a novel impact in our health. Heterogeneous photocatalysis is a promising way of degrading volatile organic compounds (VOCs) that makes the quest of new and improved photocatalysts of great importance. Herein, perovskite-related materials ATiO3 with A = Mg, Ni, Co, Zn were synthesized through an ethylene glycol-mediated root, with ethylene glycol being used as a solvent and ligand. Characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy, and energy dispersive X-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM), UV-vis spectroscopy, Raman spectroscopy, Fourier transform infrared (FT-IR), and photoluminescence spectroscopy (PL) were used in order to confirm the structure, the nanorod morphology, their absorption in UV-vis, and the separation efficiency of photogenerated charge carriers. The highest photoactivity was observed for ZnTiO3 in which 62% of toluene wa...
Page 1. UV-Optical and microstructural properties of MgF2-and LaF3-coatings deposited by IBS and ... more Page 1. UV-Optical and microstructural properties of MgF2-and LaF3-coatings deposited by IBS and PVD processes Detlev Ristau7, Stefan Günster7, Salvador Bosch2, Angela Duparré3, Enrico Masetti4, Josep Ferré-Borrull2 ...
Nanostructures: Synthesis, Functional Properties and Applications, 2003
The interest on nanocrystalline films, as a result of their outstanding properties associated wit... more The interest on nanocrystalline films, as a result of their outstanding properties associated with nanoscale and interface effects, has been recently extended to a range of metal oxides such as InOx and ZnO. These oxides are known for their fabrication simplicity, their high transparency in the visible and high reflectivity in the infrared regions, and have attracted a pronounced attention due to their remarkable room temperature sensing properties to reactive atmospheres such as Ozone. They exhibit changes in conductivity from five to eight orders of magnitude, after photoreduction with UV or laser irradiation and subsequent oxidation in reactive atmosphere, in a fully reversible manner. This combination of optical and electrical properties favors numerous applications as transparent conductive electrodes in flat panel devices and solar cells, coatings for architectural glasses and, more recently, as grating materials in optoelectronic devices.
The electrical and ozone sensor response characteristics of indium oxide, prepared by dc sputteri... more The electrical and ozone sensor response characteristics of indium oxide, prepared by dc sputtering, are reviewed in this work. The electrical conductivity of these films is compared to those obtained from other deposition techniques, and found to depend upon the synthesis technique and the deposition parameters. Our sputtered-InOx films exhibit conductivity changes of up to seven orders of magnitude under the processes of photoreduction and oxidation. A conductivity value of σ = 1.5 . 10 2 Ω -1. cm -1 has been achieved at room temperature, which provides the possibility to use this material as interconnect in ICs and as a sensor at ambient conditions without additional heating. The sensing properties towards ozone of these films are also investigated. Optimum operating temperatures have been found where the response to ozone of InOx is greater and stable. The best performance of the sensitivity of our films is found at room temperature, and is of the order of 4.10 6 . This can be a...
This paper presents an optical sensor structure for microposition detection application using tra... more This paper presents an optical sensor structure for microposition detection application using transparent electrodes of indium doped ZnO (IZO). The optical microsensor consists of two linear arrays of metal – semiconductor – metal (MSM) silicon photodetectors with IZO transparent electrodes integrated with a polymer optical waveguide.IZO layers with a thickness of 460–580 nm have been deposited by dc magnetron sputtering technique
Metal organic molecular beam epitaxy (MOMBE) InxGa1-xP/GaAs (0.45<x<0.55) interfaces and ep... more Metal organic molecular beam epitaxy (MOMBE) InxGa1-xP/GaAs (0.45<x<0.55) interfaces and epilayers have been investigated using SEM, EDX and cross-sectional TEM microscopy techniques. No oval defects were observed by SEM, while occasional surface roughness was associated with phase decomposition of the corresponding epilayer. The InxGa1-xP/GaAs interfaces were perfect, with no dislocations or planar defects. Only very few clusters attributed to imperfection of the GaAs substrate were detected and their density was estimated to be less than 106 cm-1. In the InxGa1-xP overlayer with x=0.45 ( Delta a/a=3.6*10-3) TEM has shown a structure completely free of linear or planar defects and with only a fine-scale contrast of 100 AA periodicity perpendicular to the interface along the (001) crystallographic direction. This is attributed to statistical fluctuations in the distribution of atoms with different covalent radii. For x=0.55 ( Delta a/a=3.7*10-3) the InxGa1-xP overlayer exhibits spinodal decomposition along the (001) direction, while for x=0.49 a columnar structure in the first 700 AA followed by a mottled contrast resembling that of polycrystalline films was detected.
Al-doped NiO (NiO:Al) has attracted the interest of researchers due to its excellent optical and ... more Al-doped NiO (NiO:Al) has attracted the interest of researchers due to its excellent optical and electrical properties. In this work, NiO:Al films were deposited on glass substrates by the radio frequencies (rf) sputtering technique at room temperature and they were tested against ozone gas. The Oxygen content in (Ar-O2) plasma was varied from 2% to 4% in order to examine its effect on the gas sensing performance of the films. The thickness of the films was between 160.3 nm and 167.5 nm, while the Al content was found to be between 5.3 at% and 6.7 at%, depending on the oxygen content in plasma. It was found that NiO:Al films grown with 4% O2 in plasma were able to detect 60 ppb of ozone with a sensitivity of 3.18% at room temperature, while the detection limit was further decreased to 10 ppb, with a sensitivity of 2.54%, at 80 °C, which was the optimum operating temperature for these films. In addition, the films prepared in 4% O2 in plasma had lower response and recovery time compa...
The increasing air pollution taking place in virtue of human activity has a novel impact in our h... more The increasing air pollution taking place in virtue of human activity has a novel impact in our health. Heterogeneous photocatalysis is a promising way of degrading volatile organic compounds (VOCs) that makes the quest of new and improved photocatalysts of great importance. Herein, perovskite-related materials ATiO3 with A = Mg, Ni, Co, Zn were synthesized through an ethylene glycol-mediated root, with ethylene glycol being used as a solvent and ligand. Characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy, and energy dispersive X-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM), UV-vis spectroscopy, Raman spectroscopy, Fourier transform infrared (FT-IR), and photoluminescence spectroscopy (PL) were used in order to confirm the structure, the nanorod morphology, their absorption in UV-vis, and the separation efficiency of photogenerated charge carriers. The highest photoactivity was observed for ZnTiO3 in which 62% of toluene wa...
Page 1. UV-Optical and microstructural properties of MgF2-and LaF3-coatings deposited by IBS and ... more Page 1. UV-Optical and microstructural properties of MgF2-and LaF3-coatings deposited by IBS and PVD processes Detlev Ristau7, Stefan Günster7, Salvador Bosch2, Angela Duparré3, Enrico Masetti4, Josep Ferré-Borrull2 ...
Nanostructures: Synthesis, Functional Properties and Applications, 2003
The interest on nanocrystalline films, as a result of their outstanding properties associated wit... more The interest on nanocrystalline films, as a result of their outstanding properties associated with nanoscale and interface effects, has been recently extended to a range of metal oxides such as InOx and ZnO. These oxides are known for their fabrication simplicity, their high transparency in the visible and high reflectivity in the infrared regions, and have attracted a pronounced attention due to their remarkable room temperature sensing properties to reactive atmospheres such as Ozone. They exhibit changes in conductivity from five to eight orders of magnitude, after photoreduction with UV or laser irradiation and subsequent oxidation in reactive atmosphere, in a fully reversible manner. This combination of optical and electrical properties favors numerous applications as transparent conductive electrodes in flat panel devices and solar cells, coatings for architectural glasses and, more recently, as grating materials in optoelectronic devices.
The electrical and ozone sensor response characteristics of indium oxide, prepared by dc sputteri... more The electrical and ozone sensor response characteristics of indium oxide, prepared by dc sputtering, are reviewed in this work. The electrical conductivity of these films is compared to those obtained from other deposition techniques, and found to depend upon the synthesis technique and the deposition parameters. Our sputtered-InOx films exhibit conductivity changes of up to seven orders of magnitude under the processes of photoreduction and oxidation. A conductivity value of σ = 1.5 . 10 2 Ω -1. cm -1 has been achieved at room temperature, which provides the possibility to use this material as interconnect in ICs and as a sensor at ambient conditions without additional heating. The sensing properties towards ozone of these films are also investigated. Optimum operating temperatures have been found where the response to ozone of InOx is greater and stable. The best performance of the sensitivity of our films is found at room temperature, and is of the order of 4.10 6 . This can be a...
This paper presents an optical sensor structure for microposition detection application using tra... more This paper presents an optical sensor structure for microposition detection application using transparent electrodes of indium doped ZnO (IZO). The optical microsensor consists of two linear arrays of metal – semiconductor – metal (MSM) silicon photodetectors with IZO transparent electrodes integrated with a polymer optical waveguide.IZO layers with a thickness of 460–580 nm have been deposited by dc magnetron sputtering technique
Metal organic molecular beam epitaxy (MOMBE) InxGa1-xP/GaAs (0.45<x<0.55) interfaces and ep... more Metal organic molecular beam epitaxy (MOMBE) InxGa1-xP/GaAs (0.45<x<0.55) interfaces and epilayers have been investigated using SEM, EDX and cross-sectional TEM microscopy techniques. No oval defects were observed by SEM, while occasional surface roughness was associated with phase decomposition of the corresponding epilayer. The InxGa1-xP/GaAs interfaces were perfect, with no dislocations or planar defects. Only very few clusters attributed to imperfection of the GaAs substrate were detected and their density was estimated to be less than 106 cm-1. In the InxGa1-xP overlayer with x=0.45 ( Delta a/a=3.6*10-3) TEM has shown a structure completely free of linear or planar defects and with only a fine-scale contrast of 100 AA periodicity perpendicular to the interface along the (001) crystallographic direction. This is attributed to statistical fluctuations in the distribution of atoms with different covalent radii. For x=0.55 ( Delta a/a=3.7*10-3) the InxGa1-xP overlayer exhibits spinodal decomposition along the (001) direction, while for x=0.49 a columnar structure in the first 700 AA followed by a mottled contrast resembling that of polycrystalline films was detected.
Uploads
Papers by George Kiriakidis