Number of found documents: 534
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Relation between optical and microscopic properties of hydrogenated silicon thin films with integrated germanium and tin nanoparticles
Stuchlík, Jiří; Stuchlíková, The-Ha; Čermák, Jan; Kupčík, Jaroslav; Fajgar, R.; Remeš, Zdeněk
2019 - English
The hydrogenated amorphous silicon layers (a-Si:H) were deposited by PECVD method on quartz substrates. During interruption of PECVD process the vacuum chamber was pumped up to 10-5 Pa and 1 nm thin films of Germanium or Tin were evaporated on the surface. The materials form isolated nanoparticles (NPs) on the a-Si:H surface. Then the deposited NPs were covered and stabilized by a-Si:H layer by PECVD. Those two deposition processes were alternated 5 times. The a-Si:H thin films with integrated Ge or Sn NPs were characterized optically by PDS and CPM methods, and microscopically by SEM and AFM microscopies. Optical and microscopic properties of the structures are correlated and discussed considering their application in photovoltaics.\n Keywords: thin films; a-Si:H; nanoparticles; germanium; tin Available at various institutes of the ASCR
Relation between optical and microscopic properties of hydrogenated silicon thin films with integrated germanium and tin nanoparticles

The hydrogenated amorphous silicon layers (a-Si:H) were deposited by PECVD method on quartz substrates. During interruption of PECVD process the vacuum chamber was pumped up to 10-5 Pa and 1 nm thin ...

Stuchlík, Jiří; Stuchlíková, The-Ha; Čermák, Jan; Kupčík, Jaroslav; Fajgar, R.; Remeš, Zdeněk
Fyzikální ústav, 2019

Microscopic study of multifunctional drug molecule adhesion to electronic biosensors coated with diamond and gold nanoparticles
Finsterle, T.; Pilarčíková, I.; Bláhová, I.A.; Potocký, Štěpán; Kromka, Alexander; Ukraintsev, Egor; Nepovimová, E.; Musílek, K.; Kuča, K.; Rezek, B.
2019 - English
The easy and fast detection of drug content and concentration levels is demanded in biological research as well as in clinical practice. Here we study on microscopic level how nanodiamonds and gold nanoparticles interact with a multifunctional drug molecule directly on a biosensor surface. The sensors are made of interdigitated Au electrodes coated by 5 nm hydrogenated or oxidized nanodiamonds and further combined with Au colloidal nanoparticles (size 20 nm) providing nanoscale composite (spacing 100 nm). Atomic force microscopy is employed to measure local tip-surface adhesion forces and surface topography. AFM adhesion maps show that the drug binds to all types of nanoparticles and the adhesion is also significantly influenced by the substrates on which the nanoparticles are deposited. Role of local AFM tip interaction with nanostructured surface is also discussed.\n Keywords: alzheimer drugs; biosensors; nanodiamonds; nanoparticles Fulltext is available at external website.
Microscopic study of multifunctional drug molecule adhesion to electronic biosensors coated with diamond and gold nanoparticles

The easy and fast detection of drug content and concentration levels is demanded in biological research as well as in clinical practice. Here we study on microscopic level how nanodiamonds and gold ...

Finsterle, T.; Pilarčíková, I.; Bláhová, I.A.; Potocký, Štěpán; Kromka, Alexander; Ukraintsev, Egor; Nepovimová, E.; Musílek, K.; Kuča, K.; Rezek, B.
Fyzikální ústav, 2019

Realizace nového optického tenkovrstvého ochranného prvku
Hubička, Zdeněk; Čada, Martin; Olejníček, Jiří; Kšírová, Petra; Tvarog, Drahoslav; Houha, R.; Matulová, L.
2019 - Czech
Byl vyvinut nový ochranný optický prvek s polovodivou tenkou vrstvou, která měla definované elektrické a optické vlastnosti. A new optical protection element was developed with a semiconductor thin film with defined electrical and optical properties.\n Keywords: optical thin film; sputtering; semiconductor; impedance Available at various institutes of the ASCR
Realizace nového optického tenkovrstvého ochranného prvku

Byl vyvinut nový ochranný optický prvek s polovodivou tenkou vrstvou, která měla definované elektrické a optické vlastnosti....

Hubička, Zdeněk; Čada, Martin; Olejníček, Jiří; Kšírová, Petra; Tvarog, Drahoslav; Houha, R.; Matulová, L.
Fyzikální ústav, 2019

Topological structures in ferroic materials: Book of Abstracts of the International Workshop TOPO2019
Hlinka, Jiří; Pokorný, Jan; Bubnov, Alexej
2019 - English
This is the Book of Abstracts for the International Workshop on Topological Structures in Ferroic Materials (TOPO2019 conference) held in Pruhonice-Prague on June 16-20, 2019. The special objective of the conference is expressed in the conference title: Topological Structures in Ferroic Materials. The continuous worldwide interest to this conference series is proving that it has a respected position within the series of International conferences covering all interdisciplinary field of the research. The fifth TOPO meeting in Prague 2019 was aiming to bring together the forefront science experts as well as young scientists interested in topological aspects of magnetic, superconducting, ferroelectric as well as liquid crystal matter, and mutually benefit from the beauty of the existing unifying scientific perspective. At the TOPO2019 conference more than 90 participants from 20 countries all over the world presented about 50 lectures.\n Keywords: ferroic materials; topological structures Available at various institutes of the ASCR
Topological structures in ferroic materials: Book of Abstracts of the International Workshop TOPO2019

This is the Book of Abstracts for the International Workshop on Topological Structures in Ferroic Materials (TOPO2019 conference) held in Pruhonice-Prague on June 16-20, 2019. The special objective of ...

Hlinka, Jiří; Pokorný, Jan; Bubnov, Alexej
Fyzikální ústav, 2019

MOVPE GaN/AlGaN HEMT nano-structures
Hulicius, Eduard; Kuldová, Karla; Hospodková, Alice; Pangrác, Jiří; Dominec, Filip; Humlíček, J.; Pelant, Ivan; Cibulka, Ondřej; Herynková, Kateřina
2019 - English
GaN/AlGaN-based high electron mobility transistors (HEMTs) attain better performance than their state-of-the-art full silicon-based counterparts do, offering higher power, higher frequency as well as higher temperature of operation and stability, although their voltage and current limits are somewhat lower than for the SiC-based HEMTs. GaN/AlGaN-based HEMTs are a potential choice for electric-powered vehicles, for which they are approved not only for their power parameters, but also for their good temperature stability, lifetime and reliability. It is important to optimize HEMT structures and their growth parameters to reach the optimum function for the real-world applications. HEMT structures were grown by MOVPE technology in AIXTRON apparatus on (111)-oriented single-surface polished Si substrates. Structural, optical and transport properties of the structures were measured by X-ray diffraction, optical reflectivity, time-resolved photoluminescence and micro-Raman spectroscopy.\n Keywords: GaN; MOVPE; HEMT Available at various institutes of the ASCR
MOVPE GaN/AlGaN HEMT nano-structures

GaN/AlGaN-based high electron mobility transistors (HEMTs) attain better performance than their state-of-the-art full silicon-based counterparts do, offering higher power, higher frequency as well as ...

Hulicius, Eduard; Kuldová, Karla; Hospodková, Alice; Pangrác, Jiří; Dominec, Filip; Humlíček, J.; Pelant, Ivan; Cibulka, Ondřej; Herynková, Kateřina
Fyzikální ústav, 2019

New binary refractory metal-Fe intermetallic compounds for hard magnet applications
Tchaplianka, Maxim; Shick, Alexander
2019 - English
We investigate theoretically the electronic and magnetic structure of Fe2Hf. The density functional theory is used to calculate the magnetic moments on individual atoms, the total and projected densities of states, and the magnetic anisotropy energy. The Fe2Hf is found to be metallic and ferrimagnetic, with the magnetic moments of Fe and Hf atoms pointing in the opposite directions. The negative magnetic anisotropy, and the “in-plane” preferential direction of the magnetization are found as a result of theoretical calculations. Our study suggests that the chemical control of the magnetic anisotropy has to be investigated in order to evaluate the potential of Fe2Hf for the permanent magnet applications.\n Keywords: electronic structure; magnetic anisotropy; permanent magnets Available at various institutes of the ASCR
New binary refractory metal-Fe intermetallic compounds for hard magnet applications

We investigate theoretically the electronic and magnetic structure of Fe2Hf. The density functional theory is used to calculate the magnetic moments on individual atoms, the total and projected ...

Tchaplianka, Maxim; Shick, Alexander
Fyzikální ústav, 2019

The photoluminescence and optical absorptance of plasma hydrogenated nanocrystalline ZnO thin films
Remeš, Zdeněk; Chang, Yu-Ying; Stuchlík, Jiří; Mičová, J.
2019 - English
We have developed the technology of the deposition of the nominally undoped ZnO nanocrystalline thin films by DC reactive magnetron sputtering of Zn target in the gas mixture of argon and oxygen plasma. We have optimized the photoluminescence spectroscopy for measuring optically scattering thin layers with the high sensitivity, precise sample positioning and very low influence of the scattered excitation light. Here we present the latest results on the enhancement of the photoluminescence of the nanocrystalline ZnO thin films after plasma hydrogenation. The photoluminescence in near UV region has been enhanced whereas the deep defect related photoluminescence has been significantly decreased. We found good room temperature stability of the plasma hydrogenated ZnO nanocrystals in air, but fast degradation at elevated temperature\n Keywords: nanomaterials; ZNO; photoluminescence; magnetron sputtering Available at various institutes of the ASCR
The photoluminescence and optical absorptance of plasma hydrogenated nanocrystalline ZnO thin films

We have developed the technology of the deposition of the nominally undoped ZnO nanocrystalline thin films by DC reactive magnetron sputtering of Zn target in the gas mixture of argon and oxygen ...

Remeš, Zdeněk; Chang, Yu-Ying; Stuchlík, Jiří; Mičová, J.
Fyzikální ústav, 2019

Model of carrier multiplication due to impurity impact ionization in boron-doped diamond
Mortet, Vincent; Lambert, Nicolas; Hubík, Pavel; Soltani, A.
2019 - English
Boron-doped diamond exhibits a characteristic S-shaped I-V curve at room temperature [1] with two electrical conductivity states, i.e., low and high conductivity, at high electric fields (50 – 250 kV.cm-1) due to the carrier freeze-out and impurity impact ionization avalanche effect. To our knowledge, the carrier multiplication during the change of the conductivity state has not been studied. In this article, we investigate theoretically the effect of acceptor concentration and compensation level on the carrier multiplication coefficient at room temperature to determine the optimal dopants concentration of maximum carrier multiplication. The room temperature hole concentration of boron-doped diamond has been calculated for various acceptor concentration and compensation ratio by solving numerically the charge neutrality equation within the Boltzmann approximation of the Fermi-Dirac statistic.\n Keywords: Boron-doped diamond; semiconductor; carrier multiplication coefficient; impurity impact ionization Fulltext is available at external website.
Model of carrier multiplication due to impurity impact ionization in boron-doped diamond

Boron-doped diamond exhibits a characteristic S-shaped I-V curve at room temperature [1] with two electrical conductivity states, i.e., low and high conductivity, at high electric fields (50 – 250 ...

Mortet, Vincent; Lambert, Nicolas; Hubík, Pavel; Soltani, A.
Fyzikální ústav, 2019

The peculiar outburst activity of the symbiotic binary AG Draconis
Gális, R.; Merc, J.; Leedjärv, L.; Vrašťák, M.; Karpov, Sergey
2019 - English
AG Draconis is a strongly interacting binary system which manifests characteristic symbiotic activity of alternating quiescent and active stages. The latter ones consist of the series of individual outbursts repeating at about a one-year interval. After seven years of flat quiescence following the 2006–2008 major outbursts, in the late spring of 2015, the symbiotic system AG Dra started to become brighter again toward what appeared to be a new minor outburst. The current outburst activity of AG Dra was confirmed by the following three outbursts in April 2016, May 2017 and April 2018. The photometric and spectroscopic observations suggest that all these outbursts are of the hot type. Such behaviour is considerably peculiar in almost 130-year history of observing of this object, because the major outbursts at the beginning of active stages are typically cool ones. In the present work, the current peculiar activity of the symbiotic binary AG Dra is described in detail.\n Keywords: AG Draconis; LC; outburst Fulltext is available at external website.
The peculiar outburst activity of the symbiotic binary AG Draconis

AG Draconis is a strongly interacting binary system which manifests characteristic symbiotic activity of alternating quiescent and active stages. The latter ones consist of the series of individual ...

Gális, R.; Merc, J.; Leedjärv, L.; Vrašťák, M.; Karpov, Sergey
Fyzikální ústav, 2019

Germanium and tin nanoparticles encapsulated in amorphous silicon matrix for optoelectronic application
Stuchlíková, The-Ha; Remeš, Zdeněk; Stuchlík, Jiří
2019 - English
The plasma enhanced chemical vapour deposition was combined with in situ deposition of Ge and Sn thin film by evaporation technique at surface temperature about 220 °C to form nanoparticles on the surface of hydrogenated silicon thin films to prepare diodes. Formation of nanoparticles was additionally stimulated by plasma treatment through a low pressure hydrogen glow discharge. The diodes based on PIN diode structures with and without the embedded Ge or Sn nanoparticles were characterized by temperature dependence of electrical conductivity, activation energy of conductivity, measurement of volt-ampere characteristics in dark and under solar illumination\n Keywords: Ge NPs; a-Si:H; Sn NPs; diode structures; I-V characteristics Available at various institutes of the ASCR
Germanium and tin nanoparticles encapsulated in amorphous silicon matrix for optoelectronic application

The plasma enhanced chemical vapour deposition was combined with in situ deposition of Ge and Sn thin film by evaporation technique at surface temperature about 220 °C to form nanoparticles on the ...

Stuchlíková, The-Ha; Remeš, Zdeněk; Stuchlík, Jiří
Fyzikální ústav, 2019

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