Number of found documents: 477
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The hydrogen plasma doping of ZnO thin films and nanoparticles
Remeš, Zdeněk; Neykova, Neda; Potocký, Štěpán; Chang, Yu-Ying; Hsu, H.S.
2018 - English
The optical absorptance and photoluminescence studies has been applied on the hydrogen and oxygen plasma treated, nominally undoped ZnO thin films and aligned nanocolumns grown on the nucleated glass substrate by the hydrothermal process in an oil bath containing a flask with ZnO nutrient solution. The localized defect states at 2.3 eV below the optical absorption edge were detected by photothermal deflection spectroscopy (PDS) in a broad spectral range from near UV to near IR. The optical absorptance spectroscopy shows that hydrogen doping increases free electron concentration changing ZnO to be electrically conductive (hydrogen doping).\n Keywords: ZnO; nanoparticles; hydrothermal growth; hotoluminescence spectroscopy; PDS Available at various institutes of the ASCR
The hydrogen plasma doping of ZnO thin films and nanoparticles

The optical absorptance and photoluminescence studies has been applied on the hydrogen and oxygen plasma treated, nominally undoped ZnO thin films and aligned nanocolumns grown on the nucleated glass ...

Remeš, Zdeněk; Neykova, Neda; Potocký, Štěpán; Chang, Yu-Ying; Hsu, H.S.
Fyzikální ústav, 2018

Studium cesno-hafničitého chloridu metodami termické analýzy
Král, Robert; Zemenová, Petra; Bystřický, Aleš; Vaněček, Vojtěch; Kohoutková, M.
2018 - Czech
Tato práce se zabývá studiem procesů probíhajících při tepelném zatížení připraveného chloridu cesno-hafničitého (Cs2HfCl6) a jeho monokrystalu metodami termické analýzy: simultánní diferenciální skenovací kalorimetrií a termogravimetrií (DSC-TG) a termomechanickou analýzou (TMA). Výsledky prokázaly tepelnou nestabilitu Cs2HfCl6 a jeho rozklad na chlorid cesný a hafničitý nad eutektickou teplotou.\n This work deals with the study of processes in cesium hafnium chloride (Cs2HfCl6) and its single crystal under thermal treatment by thermal analyses (different scanning calorimetry, thermogravimetry and thermomechanical analysis). Results showed thermal instability of Cs2HfCl6 and its significant decomposition to cesium and hafnium chloride above the eutectic temperature. Keywords: Cs.sub.2./sub.HfCl.sub.6./sub.; DSC-TG; TMA; krystal Available at various institutes of the ASCR
Studium cesno-hafničitého chloridu metodami termické analýzy

Tato práce se zabývá studiem procesů probíhajících při tepelném zatížení připraveného chloridu cesno-hafničitého (Cs2HfCl6) a jeho monokrystalu metodami termické analýzy: simultánní diferenciální ...

Král, Robert; Zemenová, Petra; Bystřický, Aleš; Vaněček, Vojtěch; Kohoutková, M.
Fyzikální ústav, 2018

Influence of Si doping in different layers on luminescence properties of InGaN/GaN multiple quantum well structure
Hájek, František; Hospodková, Alice; Oswald, Jiří; Slavická Zíková, Markéta
2018 - English
Luminescence of InGaN/GaN multiple quantum well (MQW) structure is strongly affected by spontaneous and piezoelectric polarizations. To suppress them, doping with shallow impurities (e. g. Si) can be used. This works presents the effects of Si doping in different layers around the MQW area. On the basis of photoluminescence and cathodoluminescence measurements and band structure simulation, the piezoelectric field is most efficiently reduced when both layers under and over MQW area are Si doped.\n Keywords: nitrides; quantum wells; luminescence; semiconductor doping Fulltext is available at external website.
Influence of Si doping in different layers on luminescence properties of InGaN/GaN multiple quantum well structure

Luminescence of InGaN/GaN multiple quantum well (MQW) structure is strongly affected by spontaneous and piezoelectric polarizations. To suppress them, doping with shallow impurities (e. g. Si) can be ...

Hájek, František; Hospodková, Alice; Oswald, Jiří; Slavická Zíková, Markéta
Fyzikální ústav, 2018

Modeling of monocrystalline magnesium microbeam bending
Němeček, J.; Maňák, Jan; Němeček, J.
2018 - English
This paper presents a numerical simulation of a micro-scale experiment on a magnesium alloy. Three dimensional numerical FE model with elastoplastic behavior respecting crystal anisotropy was used to fit experimental load displacement curves. Keywords: magnesium; microbeams; crystal anisotropy; FE model Available at various institutes of the ASCR
Modeling of monocrystalline magnesium microbeam bending

This paper presents a numerical simulation of a micro-scale experiment on a magnesium alloy. Three dimensional numerical FE model with elastoplastic behavior respecting crystal anisotropy was used to ...

Němeček, J.; Maňák, Jan; Němeček, J.
Fyzikální ústav, 2018

Characterization of hydrogenated silicon thin films and diode structures with integrated germanium nanoparticles
Stuchlík, Jiří; Fajgar, Radek; Kupčík, Jaroslav; Remeš, Zdeněk; Stuchlíková, The-Ha
2018 - English
Substrates with ZnO (or ITO) conductive layers were covered by thin film of a-Si:H deposited by PECVD technique. Under a turbo-molecular vacuum (10-4 Pa) the reactive laser ablation (RLA) was used to cover this a-Si:H thin film by germanium NPs. The RLA was performed using focused excimer ArF laser beam (193 nm, 100 mJ/pulse) under SiH4 background atmosphere (0.5 Pa). As a target the elemental germanium was used. Reaction between ablated Ge and silane led to formation of Ge NPs covered by thin SiGe layer. Then the deposited NPs were covered and stabilized by a-Si:H layer by PECVD. Those two deposition processes was alternated and applied a few times. The Si:H thin films with integrated Ge NPs were characterized by microscopic, spectroscopic and diffraction techniques. I-V characteristics of final diode structures without and under illumination were measured as well as their electroluminescence behaviour. Keywords: PECVD; a-Si:H diode structures; Ge; nanoparticles Available at various institutes of the ASCR
Characterization of hydrogenated silicon thin films and diode structures with integrated germanium nanoparticles

Substrates with ZnO (or ITO) conductive layers were covered by thin film of a-Si:H deposited by PECVD technique. Under a turbo-molecular vacuum (10-4 Pa) the reactive laser ablation (RLA) was used to ...

Stuchlík, Jiří; Fajgar, Radek; Kupčík, Jaroslav; Remeš, Zdeněk; Stuchlíková, The-Ha
Fyzikální ústav, 2018

Histology and micro-CT study of diamond-coated metal bone implants
Potocký, Štěpán; Ižák, Tibor; Dragounová, Kateřina; Kromka, Alexander; Rezek, Bohuslav; Mandys, V.; Bartoš, M.; Bačáková, Lucie; Sedmera, David
2018 - English
A conformal coating of a thin diamond layer on three-dimensional metal bone implants was shown directly on stainless steel and TiAl6V4 cortical screw implant using ultrasonic and composite polymer pretreatment method. The best conformation coverage was achieved in the case of the WO3 interlayer for both stainless steel and TiAl6V4 screws. The process of osteointegration of the screw implants into rabbit femurs is evidenced by the formation of a bone edge via desmogenous ossification around the screws in less than six months after implantation. A detailed evaluation of the tissue reaction around the implanted screws shows good biocompatibility of diamond-coated metal bone implants. Keywords: screw implant; diamond coating; osteointegration; histology Available at various institutes of the ASCR
Histology and micro-CT study of diamond-coated metal bone implants

A conformal coating of a thin diamond layer on three-dimensional metal bone implants was shown directly on stainless steel and TiAl6V4 cortical screw implant using ultrasonic and composite polymer ...

Potocký, Štěpán; Ižák, Tibor; Dragounová, Kateřina; Kromka, Alexander; Rezek, Bohuslav; Mandys, V.; Bartoš, M.; Bačáková, Lucie; Sedmera, David
Fyzikální ústav, 2018

Electronic transfer between nanostructures. Negative differential resistance in conductive polymers.
Král, Karel; Menšík, Miroslav
2018 - English
The effect of negative differential resistance can be observed experimentally in some material systems based on polymers. These observation are explained usually to be due to the presence of certain carrier traps which can capture the carriers of the electric current. In the present theoretical work we are going to show that besides this carrier trapping origin of the negative differential resistance there can also be an intrinsic mechanism present, causing such an effect. Namely, instead of the traps, the electron-phonon interaction can cooperate with the tunneling of the charge carriers between their localized states and can provide the effect the negative differential resistance. This electron-phonon interaction is included in a non-perturbative way. The theory will be briefly summarized and explained. Keywords: electronic transfer; charge transfer; nanostructures; quantum dots; nonequilibrium transport theory Available at various institutes of the ASCR
Electronic transfer between nanostructures. Negative differential resistance in conductive polymers.

The effect of negative differential resistance can be observed experimentally in some material systems based on polymers. These observation are explained usually to be due to the presence of certain ...

Král, Karel; Menšík, Miroslav
Fyzikální ústav, 2018

Characterization and tribological testing of a carbon-based nanolayer prepared by ion beam assisted deposition
Horažďovský, T.; Kovač, J.; Drbohlav, Ivo
2017 - English
Carbon-based nanolayers have been attracting much attention due to their excellent low-friction properties, their high hardness and their good wear resistance. In this work we present the results of material research aimed at reducing the friction of the functional surfaces of titanium implants, and thus extending their lifetime to reoperation. An analysis of the chemical composition showed that the modified surface is composed of a carbon-based nanolayer, a mixed interface, and a nitrogen-enriched sublayer. Raman spectroscopy showed the DLC character of the carbon-based nanolayer with sp2 rich bonds. A TiN compound was detected by X-ray diffraction in the modified surface area.\n Keywords: nanolayer; friction; nanohardness Available at various institutes of the ASCR
Characterization and tribological testing of a carbon-based nanolayer prepared by ion beam assisted deposition

Carbon-based nanolayers have been attracting much attention due to their excellent low-friction properties, their high hardness and their good wear resistance. In this work we present the results of ...

Horažďovský, T.; Kovač, J.; Drbohlav, Ivo
Fyzikální ústav, 2017

Mechanical properties of Cr-DLC layers prepared by hybrid laser technology
Písařík, Petr; Jelínek, Miroslav; Remsa, J.; Tolde, Z.
2017 - English
Diamond like carbon (DLC) layers have excellent biological properties for use in medicine for coating implants, but poor adhesion to biomedical alloys (titanium alloys, chromium alloys and stainless steel). The adhesion can be improved by doping the DLC layer by chromium, as described in this article. Chromium doped diamond like carbon layers (Cr DLC) were deposited by hybrid deposition system using KrF excimer laser (deposition diamond like carbon - graphite target) and\nmagnetron sputtering (deposition chromium - chromium target). Carbon and chromium contents were determined by wavelength dispersive X-ray spectroscopy.\n Keywords: DLC; chromium doped; mechanical properties; PLD Available at various institutes of the ASCR
Mechanical properties of Cr-DLC layers prepared by hybrid laser technology

Diamond like carbon (DLC) layers have excellent biological properties for use in medicine for coating implants, but poor adhesion to biomedical alloys (titanium alloys, chromium alloys and stainless ...

Písařík, Petr; Jelínek, Miroslav; Remsa, J.; Tolde, Z.
Fyzikální ústav, 2017

Correlated microscopy of electronic and material properties of graphene grown on diamond thin films
Rezek, Bohuslav; Čermák, Jan; Varga, Marián; Tulic, S.; Skákalová, V.; Waitz, T.; Kromka, Alexander
2017 - English
In this work we compare growth of graphene on diamond thin films that enable large area processing. We use films with different crystal size and surface roughness to obtain deeper insight into formation and properties of GoD. The diamond films are coated by a nm thin sputtered Ni layer and heated to 900°C in a forming gas atmosphere (H2/Ar) to initiate catalytic thermal CVD process. The samples are cleaned from residual Ni after the growth process. We employ scanning electron microscopy, Raman micro-spectroscopy and Kelvin probe force microscopy to correlate material, structural, and electronic properties of graphene on diamond. We show how grain size and grain boundaries influence graphene growth and material and electronic properties. For instance we show that the grain boundaries (with non-diamond carbon phases) in diamond films have an important role. They influence the electronic properties and they are beneficial for forming graphene on diamond higher quality. Keywords: graphene; diamond; microscopy; micro-spectroscopy; electronic properties Available at various institutes of the ASCR
Correlated microscopy of electronic and material properties of graphene grown on diamond thin films

In this work we compare growth of graphene on diamond thin films that enable large area processing. We use films with different crystal size and surface roughness to obtain deeper insight into ...

Rezek, Bohuslav; Čermák, Jan; Varga, Marián; Tulic, S.; Skákalová, V.; Waitz, T.; Kromka, Alexander
Fyzikální ústav, 2017

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