Number of found documents: 623
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LOW SUPERSATURATION OVERGROWTH OF NANOPOROUS GaAs SUBSTRATES
Nohavica, Dušan; Grym, Jan; Gladkov, Petar; Hamplová, Marie
2012 - English
Oriented pore networks in GaAs were created by electrochemical dissolution. Low supersaturation overgrowth of the porous substrates by InxGa1-xAs (x<4%) was realized by Liquid Phase Epitaxy (LPE) Keywords: Porous III-V semiconductors; Electrochemical etching; Pores conversion Available at various institutes of the ASCR
LOW SUPERSATURATION OVERGROWTH OF NANOPOROUS GaAs SUBSTRATES

Oriented pore networks in GaAs were created by electrochemical dissolution. Low supersaturation overgrowth of the porous substrates by InxGa1-xAs (x<4%) was realized by Liquid Phase Epitaxy (LPE)

Nohavica, Dušan; Grym, Jan; Gladkov, Petar; Hamplová, Marie
Ústav fotoniky a elektroniky, 2012

Development of bragg fibers for transfer of laser radiation at
Matějec, Vlastimil; Kašík, Ivan; Podrazký, Ondřej; Aubrecht, Jan; Frank, M.; Jelínek, M.; Kubeček, V.
2012 - English
Keywords: optical fiber sensor; photocatalysis; toluene Available at various institutes of the ASCR
Development of bragg fibers for transfer of laser radiation at

Matějec, Vlastimil; Kašík, Ivan; Podrazký, Ondřej; Aubrecht, Jan; Frank, M.; Jelínek, M.; Kubeček, V.
Ústav fotoniky a elektroniky, 2012

Graphite/n-InP Schottky barrier with electrophoretically deposited Pt nanoparticles for hydrogen and nitrogen-monoxide detection
Žďánský, Karel; Vaniš, Jan; Černohorský, Ondřej; Kacerovský, Pavel; Fojtík, A.
2012 - English
N-type InP was deposited with Pt nanoparticles (NPs) by electrophoresis. The Pt NPs density was varied from a tenth of monolayer to several monolayers. Schottky contacts were made by colloidal graphite on the InP wafer site covered with Pt NPs. It was observed that H2 was detected by an increase of the current while NO was detected by its decrease. For explanation, we discuss mechanism which involves negative charging of adsorbed H atoms with electrons by increasing affinity level due to correlation efects Keywords: semiconductor devices; nanostructures; sensors Available in a digital repository NRGL
Graphite/n-InP Schottky barrier with electrophoretically deposited Pt nanoparticles for hydrogen and nitrogen-monoxide detection

N-type InP was deposited with Pt nanoparticles (NPs) by electrophoresis. The Pt NPs density was varied from a tenth of monolayer to several monolayers. Schottky contacts were made by colloidal ...

Žďánský, Karel; Vaniš, Jan; Černohorský, Ondřej; Kacerovský, Pavel; Fojtík, A.
Ústav fotoniky a elektroniky, 2012

LAYERS OF METALS NANOPARTICLES ON VARIOUS SEMICONDUCTORS FOR HYDROGEN DETECTION
Černohorský, Ondřej; Žďánský, Karel; Yatskiv, Roman; Grym, Jan
2012 - English
Metal nanoparticles have many interesting properties which is given by their space restriction. Their large active surface is very well exploited during catalysis. Pd and Pt are metals know for their ability to dissociate molecular hydrogen on single atoms. We prepared Schottky diodes on semiconductors InP, GaN, GaAs, and InGaAs to obtain hydrogen sensor. Method of preparation such diodes is electrophoretic deposition of Pd or Pt nanoparticles from their colloid solution onto semiconductor substrate. Over the layer of nanoparticles, porous metal contact was prepared. Hydrogen molecules are dissociated on these metal nanoparticles and single atom which settles on the interface between metal and semiconductor and they increase or decrease Schottky barrier height. By this method we can measure from 1 ppm H2 in the air, where the current change is over one order of magnitude Keywords: Schottky barrier; binary semiconductors; metal nanoparticles Available on request at various institutes of the ASCR
LAYERS OF METALS NANOPARTICLES ON VARIOUS SEMICONDUCTORS FOR HYDROGEN DETECTION

Metal nanoparticles have many interesting properties which is given by their space restriction. Their large active surface is very well exploited during catalysis. Pd and Pt are metals know for their ...

Černohorský, Ondřej; Žďánský, Karel; Yatskiv, Roman; Grym, Jan
Ústav fotoniky a elektroniky, 2012

Subspace Methods in Linear DS - CDMA Detection
Šimša, Jan
2011 - English
Application of signal subspace methods in linear mean square error (MSE) detectors of direct sequence CDMA signals. Focusing on the cross-spectral (CS) method, its origin and a relation to multistage Wiener filter (MWF) is shown. This filter results from splitting of correlation matrix Keywords: spread spectrum; multiuser detectors; subspace methods Available at various institutes of the ASCR
Subspace Methods in Linear DS - CDMA Detection

Application of signal subspace methods in linear mean square error (MSE) detectors of direct sequence CDMA signals. Focusing on the cross-spectral (CS) method, its origin and a relation to multistage ...

Šimša, Jan
Ústav fotoniky a elektroniky, 2011

Preparation and characterizatiobn of layers of Au, Pd and Rh nanoparticles deposited on n-InP substrates
Kostejn, M.; Žďánský, Karel; Piksová, K.; Zavadil, Jiří
2011 - English
Colloids of Au, Pd and Rh nanoparticles (NPs) were prepared in reverse micelles and surface plasmon absorption bands were identified. Layers of metal NPs were deposited on InP substrates by electrophoretic deposition and imaged by SEM. Low-temperature photoluminescence spectrum of InP was found to be enhanced mainly by Au NPs. Sensitivity to hydrogen of Schottky barriers prepared by dropping colloidal graphite onto the surface of InP partly covered with Pd NPs was measured by current change in 100 ppm H2/N2. Keywords: semiconductor devices; nanostructures; sensors Available at various institutes of the ASCR
Preparation and characterizatiobn of layers of Au, Pd and Rh nanoparticles deposited on n-InP substrates

Colloids of Au, Pd and Rh nanoparticles (NPs) were prepared in reverse micelles and surface plasmon absorption bands were identified. Layers of metal NPs were deposited on InP substrates by ...

Kostejn, M.; Žďánský, Karel; Piksová, K.; Zavadil, Jiří
Ústav fotoniky a elektroniky, 2011

Graphite Schottky barriers on n-InP and n-GaN with deposited Pd, Pt or bimetallic Pd/Pt nanoparticles for H2 sensing
Žďánský, Karel; Muller, M.; Černohorský, Ondřej; Yatskiv, Roman
2011 - English
High Schottky barriers have been achieved by applying colloidal graphite on n-type InP and on n-type GaN semiconductor crystal wafers. The barrier heights were shown to be close to Schottky-Mott limit ad thermionic emission theory. Porous properties of the graphite Schottky contacts were demonstrated by scanning electron microscopy. Keywords: semiconductor devices; nanostructures; sensors Available at various institutes of the ASCR
Graphite Schottky barriers on n-InP and n-GaN with deposited Pd, Pt or bimetallic Pd/Pt nanoparticles for H2 sensing

High Schottky barriers have been achieved by applying colloidal graphite on n-type InP and on n-type GaN semiconductor crystal wafers. The barrier heights were shown to be close to Schottky-Mott limit ...

Žďánský, Karel; Muller, M.; Černohorský, Ondřej; Yatskiv, Roman
Ústav fotoniky a elektroniky, 2011

Study of layers of Pd on InP
Černohorský, Ondřej; Žďánský, Karel; Proška, J.
2011 - English
Pd nanoparticles were prepared in colloid solution stabilized by AOT. The layers were prepared by electrophoretic deposition through the mask of polystyrene spheres. SEM measurement showed that particles in colloid solution are separated and after deposition they form small aggregates on InP. The size of these aggregates depends on the time of deposition. I-V characteristics were measured and then Schottky barrier height and ideality factor were calculated. The morphology of layers was monitored by SEM. Keywords: semiconductor devices; nanostructures; sensors Available in a digital repository NRGL
Study of layers of Pd on InP

Pd nanoparticles were prepared in colloid solution stabilized by AOT. The layers were prepared by electrophoretic deposition through the mask of polystyrene spheres. SEM measurement showed that ...

Černohorský, Ondřej; Žďánský, Karel; Proška, J.
Ústav fotoniky a elektroniky, 2011

Time and frequency transfer in all-optical network
Smotlacha, V.; Kuna, Alexander
2011 - English
This paper describes usage of all-optical network for time metrology application - Time and frequency transfer between two geographically distant sites. Although several approaches exist, there is no production implementation yet. Our method is based on newly developed adapters utilizing channels in a DWDM (Dense Wavelength-Division Multiplexing) network. We present results of tests performed in real production all-optical network including the time transfer between atomic clocks in Prague and Vienna over more than 500 km long optical path Keywords: Time transfer; Frequency transfer; All-optical network Available on request at various institutes of the ASCR
Time and frequency transfer in all-optical network

This paper describes usage of all-optical network for time metrology application - Time and frequency transfer between two geographically distant sites. Although several approaches exist, there is no ...

Smotlacha, V.; Kuna, Alexander
Ústav fotoniky a elektroniky, 2011

Study of layers of metal nanoparticles on semiconductor wafers for hydrogen detection
Muller, M.; Žďánský, Karel; Zavadil, Jiří; Piksová, K.
2011 - English
Colloid solutions of metal Pt, Pd and Pt/Pd alloy nanoparticles by reverse micelle technique in isooctane were prepared. Layers of the nanoparticles on InP and GaN substrates using electrophoretic deposition were prepared. Metal nanoparticles in the colloid and in deposits were characterized by SEM. Schottky diodes were fabricated by application of colloidal graphite on nanoparticle layer. An increase in current in hydrogen-nitrogen mixture was measured for hydrogen concentrations between 5 and 1000 ppm. Keywords: semiconductor devices; nanostructures; sensors Available at various institutes of the ASCR
Study of layers of metal nanoparticles on semiconductor wafers for hydrogen detection

Colloid solutions of metal Pt, Pd and Pt/Pd alloy nanoparticles by reverse micelle technique in isooctane were prepared. Layers of the nanoparticles on InP and GaN substrates using electrophoretic ...

Muller, M.; Žďánský, Karel; Zavadil, Jiří; Piksová, K.
Ústav fotoniky a elektroniky, 2011

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