J. Vaniš - Academia.edu (original) (raw)
Papers by J. Vaniš
Bulletin of Materials Science, 2021
Metal-oxide-based sensors (MOS) can be used for several technological applications in microelectr... more Metal-oxide-based sensors (MOS) can be used for several technological applications in microelectronics, due to their low cost and sensitive capabilities to different chemical species. On the perspective to develop CuO-TiO 2 MOS, our goal was to obtain a homogeneous intermixing of Cu and Ti in the bulk structure of the detectors, exploring the most promising combination between such elements and avoiding the presence of Cu-Ti-O compounds. To do that, several Cu and Ti thin layers were alternatively deposited by Ar ? sputtering on silicon wafers and, subsequently, oxidized by thermal annealing. The obtained samples were characterized in terms of %at. Cu-Ti ratios (by RBS and SIMS analyses) and morphology (by AFM and SEM investigations), showing the abundance ratios of such elements in the whole structure. In particular, SIMS maps allowed to study the spatial distribution and thickness of each phase of the Cu-Ti multilayers and further to observe the Cu diffusion and the mixing with Ti, as well as phase separation of CuO and TiO 2 in the samples. This unwanted effect represents an open issue that has to be investigated, in order to improve the MOS fabrication.
Some properties of thermoelectric nano-layers prepared by Pulsed Laser Deposition from hot presse... more Some properties of thermoelectric nano-layers prepared by Pulsed Laser Deposition from hot pressed Bi2Te3 target are presented. The layers were prepared under various deposition conditions that include the substrate temperature during the deposition and the laser beam density, to study its influence on the quality of the surface. Crystallinity, composition and morphology of the layers are presented. Transport and thermoelectric properties such as electrical resistivity, the Seebeck coefficient, power factor and the thermoelectric figure of merit for the smoothest layers prepared at substrate temperature of 200 °C applying laser beam density 3 Jcm-2 are also given. Nano crystallites observed on the layer’s surface are studied by X-ray Diffraction and by Atomic Force Microscope. The problematic of a new method for a relative thermal conductivity characterization of thin thermoelectric layers and multi-layered structures in nanometre range using a scanning thermal microcsope working in...
Phosphorus, Sulfur, and Silicon and the Related Elements, 2020
On the perspective to develop CuO–TiO2 MOS, multilayered Cu and Ti thin layers were alternatively... more On the perspective to develop CuO–TiO2 MOS, multilayered Cu and Ti thin layers were alternatively deposited on silicon wafers using 25 keV Ar + ion beam sputtering and, subsequently, oxidized by thermal annealing in air at 400 °C for 24 h. The deposited films have variable ratios of the Cu and Ti % at. One of the main goal is to obtain such multilayers avoiding the presence of Cu–Ti–O compounds. The samples were characterized in terms of composition (by RBS and SIMS analyses) and morphology (by AFM and SEM investigations). In particular, SIMS maps allows to observe the spatial distribution and thickness of each phase of the Cu/Ti multilayers, and further to observe Cu diffusion and mixing with Ti, as well as phase separation of CuO and TiO2 in the samples. The reasons of this effect represent an open issue that has to investigated, in order to improve the MOS fabrication. GRAPHICAL ABSTRACT
Physica E: Low-dimensional Systems and Nanostructures, 2021
Chemosensors, 2021
Chemiresistors based on thin films of the Li-doped CuO–TiO2 heterojunctions were synthesized by a... more Chemiresistors based on thin films of the Li-doped CuO–TiO2 heterojunctions were synthesized by a 2-step method: (i) repeated ion beam sputtering of the building elements (on the Si substrates and multisensor platforms); and (ii) thermal annealing in flowing air. The structure and composition of the films were analyzed by several methods: Rutherford Backscattering (RBS), Neutron Depth Profiling (NDP), Secondary Ion Mass Spectrometry (SIMS), and Atomic Force Microscopy (AFM), and their sensitivity to gaseous analytes was evaluated using a specific lab-made device operating in a continuous gas flow mode. The obtained results showed that the Li doping significantly increased the sensitivity of the sensors to oxidizing gases, such as NO2, O3, and Cl2, but not to reducing H2. The sensing response of the CuO–TiO2–Li chemiresistors improved with increasing Li content. For the best sensors with about 15% Li atoms, the detection limits were as follows: NO2 → 0.5 ppm, O3 → 10 ppb, and Cl2 → 0...
Crystals, 2019
One dimensional ZnO nanostructures prepared by favorable and simple solution growth methods are a... more One dimensional ZnO nanostructures prepared by favorable and simple solution growth methods are at the forefront of this research. Vertically oriented ZnO nanorods with uniform physical properties require high-quality seed layers with a narrow size distribution of the crystallites, strong c-axis orientation, and low surface roughness and porosity. It has been shown that high quality seed layers can be prepared by the sol–gel process. The sol–gel process involves three essential steps: preparation of the sol, its deposition by dip coating, and thermal treatment comprising preheating and annealing. We put emphasis on the investigation of the heat treatment on the properties of the seed layers and on the vertical alignment of the nanorods. It was demonstrated that for the vertical alignment of the nanorods, the preheating step is crucial and that the temperatures reported in the literature have been too low. With higher preheating temperatures, conditions for the vertical alignment of ...
Applied Physics A, 2016
Thermal conductivity of thermoelectric \hbox {Bi}_{2}\hbox {Te}_{3}$$Bi2Te3 and \hbox {Yb}_{0... more Thermal conductivity of thermoelectric \hbox {Bi}_{2}\hbox {Te}_{3}$$Bi2Te3 and \hbox {Yb}_{0.19}\hbox {Co}_{4}\hbox {Sb}_{12}$$Yb0.19Co4Sb12 thin nanolayers of different thicknesses prepared by pulsed laser deposition on Si (100) substrates was studied by a scanning thermal microscope working in AC current pulse mode. A sensitivity of the approach is demonstrated on the steep Si substrate-layer boundary made by a Ga+ focused ion beam technique. Transport and thermoelectric properties such as in-plane electrical resistivity and the Seebeck coefficient were studied in temperature range from room temperature up to 200\,{}^{\circ }\hbox {C}$$200∘C. The room temperature thermal conductivity of the layers was estimated from thermoelectric figure of merit that was measured by the Harman technique, in which parameters related to electrical conductivity, Seebeck coefficient and thermal conductivity are measured at the same place and at the same time with electrical current flowing through the layer. For \hbox {Yb}_{0.19}\hbox {Co}_{4}\hbox {Sb}_{12}$$Yb0.19Co4Sb12 and \hbox {Bi}_{2}\hbox {Te}_{3}$$Bi2Te3 layers, we observed room temperature electrical resistivity of about 7 and 1\,\hbox {m}\Omega \,\hbox {cm}$$1mΩcm, the Seebeck coefficient of -112$$-112 and -61\,\upmu \hbox {VK}^{-1}$$-61μVK-1, thermoelectric figure of merit about 0.04 and 0.13 and we estimated thermal conductivity of about 1.3 and 0.9\,\hbox {WK}^{-1}\hbox {m}^{-1}$$0.9WK-1m-1, respectively.
Journal of Materials Science and Chemical Engineering, 2016
Thermoelectric layers as Bi 2 Te 3 , Yb 0.19 Co 4 Sb 12 , FeSb 2 Te, Ce 0.1 Fe 0.7 Co 3.3 Sb 12 a... more Thermoelectric layers as Bi 2 Te 3 , Yb 0.19 Co 4 Sb 12 , FeSb 2 Te, Ce 0.1 Fe 0.7 Co 3.3 Sb 12 and FeSb 2 Te/Ce 0.1 Fe 0.7 Co 3.3 Sb 12 multilayers were prepared by Pulsed Laser Deposition (PLD). Smooth, nano-crystalline, stoichiometric layers were synthetized in a classical PLD arrangement or in a special off-axis PLD arrangement, followed by Rapid thermal annealing. Results of physical characterizations such as morphology-Atomic Force Microscope, Scanning Electron Microscope, composition-Energy Dispersive X-ray analysis, crystallinity-X-ray Diffraction, separation of multilayers-Secondary of ion beam mass spectroscopy SIMS and study of thermoelectric properties such as the thermoelectric figure of merit ZT, in-plane electrical resistivity, Seebeck coefficient and thermal conductivity are presented. For thermal conductivity measurement a newly developed Atomic force thermal microscope (AFMTh) was tested. Results obtained on the single layers compared to multi-layered structures are discussed.
![Research paper thumbnail of Characterization and nanometer-scale modifications of Bi[sub 2]Te[sub 3] surface via atomic force microscopy](https://attachments.academia-assets.com/95064435/thumbnails/1.jpg)
](Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000
The structure of the basal plane of a Bi 2 Te 3 crystal surface was studied by means of the atomi... more The structure of the basal plane of a Bi 2 Te 3 crystal surface was studied by means of the atomic force microscopy ͑AFM͒ technique. The measured heights of steps, ranging from 0.2 to 1.4 nm, were in agreement with other structural data of Bi 2 Te 3. The images of freshly cleaved surface, obtained with atomic resolution, revealed a plane of tellurium atoms. The recorded interatomic distances of 0.42Ϯ0.02 nm were also in accordance with the structural data. We also showed that there is a possibility of surface nanostructures formation using the AFM probe, when working above force threshold value.
Journal of Electronic Materials, 2015
We present the development and results of a new simple method for thermal conductivity characteri... more We present the development and results of a new simple method for thermal conductivity characterization of thin films and thermoelectric structures using a scanning thermal microscope in pulsed current mode. The presented method does not allow measurement of absolute thermal conductivity of the studied system, but only relative to the Si substrate. We present the results of the method on the Si substrate/layer step boundary. The nano-layers of different thickness and different materials were prepared for the experiments by the pulsed laser deposition from hot-pressed targets.
Indian journal of experimental biology, 2008
Hypothesis of coherent vibration states in biological systems based on nonlinear interaction betw... more Hypothesis of coherent vibration states in biological systems based on nonlinear interaction between longitudinal elastic and electric polarization fields with metabolic energy supply was formulated by Frohlich. Conditions for excitation of coherent states and generation of electromagnetic fields are satisfied in microtubules which form electrical polar structures. Numerical models are used for analysis of Frohlich's vibration states in cells. Reduction of activity and of energy production in mitochondria, and disintegration of cytoskeleton structures by phosphorylation on the pathway of cancer trasformation can diminish excitation of the Frohlich's vibration states and of the generated electromagnetic field, which results in disturbances of the interaction forces between cells. Interaction forces between cancer cells may be smaller than interaction forces between healthy cells and cancer cells as follows from numerical models. Mechanism of malignity, i.e. local invasion, de...
NATO Science for Peace and Security Series A: Chemistry and Biology, 2014
The properties of very thin Bi2Te3 (nano-) layers of different thickness prepared by pulsed laser... more The properties of very thin Bi2Te3 (nano-) layers of different thickness prepared by pulsed laser deposition at different fluences are presented. Thermoelectric properties such as the thermal conductivity, the in-plain electrical conductivity, the Seebeck coefficient and also crystallinity, composition and morphology are presented. The surface properties were studied by atomic force microscopy.
Proceedings ICT'03. 22nd International Conference on Thermoelectrics (IEEE Cat. No.03TH8726), 2003
Transport properties are presented for 60nm thick layers which were prepared by the laser ablatio... more Transport properties are presented for 60nm thick layers which were prepared by the laser ablation from a Bi2Te3 target. The layers are deposited on quartz glass substrates. The energy density of the laser beam I on the target is 2Jcm-2 and the temperature of the substrate during deposition varies between (200-480°C) for different samples. The influence of the temperature of
Laser Physics, 2014
ABSTRACT A method for relative thermal conductivity characterization of thin thermoelectric layer... more ABSTRACT A method for relative thermal conductivity characterization of thin thermoelectric layers and multi-layered structures in nanometre range using a scanning thermal microscope working in an active constant current mode is suggested. The method requires a very smooth and high quality surface of the studied thermoelectric system. To fulfil these requirements a study of the influence of principal deposition conditions including substrate temperature and laser beam density on surface quality of Bi2Te3 layers prepared by pulsed laser deposition was performed and its results are presented.
2006 25th International Conference on Thermoelectrics, 2006
Bulk Yb0.19Co4Sb12 skutterudite prepared by hot pressing was found to be a good high temperature ... more Bulk Yb0.19Co4Sb12 skutterudite prepared by hot pressing was found to be a good high temperature thermoelectric material with a high figure of merit ZT (ZT=1.2 at T=650 K). In this contribution the properties of thin layers prepared by pulsed laser deposition from such target are presented. The target was prepared by hot pressing and was proved to be a skutterudite
ECS Transactions, 2013
We report on the electrochemical preparation of GaAs porous substrates, their heat treatment in A... more We report on the electrochemical preparation of GaAs porous substrates, their heat treatment in As rich environment and their overgrowth by metalorganic vapor phase epitaxy (MOVPE). The goal is to demonstrate that porous substrates are capable of accommodating strain at the interface with lattice mismatched In(x)Ga(1-x)As layers.
PIERS Online, 2007
Cytoskeleton with microtubules is the main organization structure of the eukaryotic cell. Possibl... more Cytoskeleton with microtubules is the main organization structure of the eukaryotic cell. Possible sources of vibrational excitations of electrically polar cytoskeleton components are enumerated. Temperature stabilized, triple screened box (electrically and electromagnetically by mumetal) with point sensor and preamplifiers was used for measurement of electrical oscillations of yeast cell. Preliminary findings of the electrical measurement and local nanomechanical AFM measurements are presented. Findings correspond to the Frölich's postulate of coherent electrically polar longitudinal vibrations in biological systems.
physica status solidi (c), 2012
We report on the electrochemical preparation of porous GaAs substrates suited for the lattice mis... more We report on the electrochemical preparation of porous GaAs substrates suited for the lattice mismatched epitaxial growth from the liquid and vapour phase The aim is to gain control over the uniformity of the pore nucleation layer and pore branching below this layer to achieve structures with a high degree of porosity and periodicity. The etching process should be surface-friendly and leave minimum damage on the substrate surface to be ready for the subsequent epitaxial growth. We show that surfaces with different pore diameter, pore spacing and surface roughness can be achieved by careful selection of the etching regime, electrolyte, and substrate. Moreover, the pore depth, pore density and pore branching can be tailored to comply with the subsequent epitaxial growth.
Physica E: Low-dimensional Systems and Nanostructures, 2013
ABSTRACT Density of states is studied by a ballistic electron emission microscopy/spectroscopy on... more ABSTRACT Density of states is studied by a ballistic electron emission microscopy/spectroscopy on self-assembled InAs quantum dots embedded in GaAs/AlGaAs heterostructure prepared by metal–organic vapor phase epitaxy. An example of integral quantum dot density of states which is proportional to superposition of a derivative of ballistic current–voltage characteristics measured at every pixel (1.05 nm×1.05 nm) of quantum dot is presented. For the two lowest observed energy levels of quantum dot (the maxima in density of states) the density of states is mapped and correlated with the shape of quantum dot. It was found that prepared quantum dots have a few peaks on their flatter top and a split of the lowest energy level can be observed. This effect can be explained by inhomogeneous (nonuniform) stress distribution in the examined quantum dot.
Journal of Physics: Conference Series, 2014
Multi-layered Ce 0.09 Fe 0.67 Co 3.33 Sb 12 /FeSb 2.1 Te structures composed of thin equidistant ... more Multi-layered Ce 0.09 Fe 0.67 Co 3.33 Sb 12 /FeSb 2.1 Te structures composed of thin equidistant layers were prepared by Pulsed Laser Deposition on fused silica quartz glass substrates. The structures were prepared at different substrate temperatures (230 °C or 250 °C) applying the laser beam energy density of 3 Jcm-2. In the contribution we present some thermoelectric properties such as the in-plane electrical conductivity, the Seebeck coefficient and the power factor for the multi-layered structures in the temperature range from 300 K to 500 K. Comparison of multi-layered structure's thermoelectric properties with single thin Ce 0.09 Fe 0.67 Co 3.33 Sb 12 and FeSb 2.1 Te layers is given. A cross sectional picture of the multilayered structure made by Scanning Electron Microscope is presented for the thicker multilayered structure.
Bulletin of Materials Science, 2021
Metal-oxide-based sensors (MOS) can be used for several technological applications in microelectr... more Metal-oxide-based sensors (MOS) can be used for several technological applications in microelectronics, due to their low cost and sensitive capabilities to different chemical species. On the perspective to develop CuO-TiO 2 MOS, our goal was to obtain a homogeneous intermixing of Cu and Ti in the bulk structure of the detectors, exploring the most promising combination between such elements and avoiding the presence of Cu-Ti-O compounds. To do that, several Cu and Ti thin layers were alternatively deposited by Ar ? sputtering on silicon wafers and, subsequently, oxidized by thermal annealing. The obtained samples were characterized in terms of %at. Cu-Ti ratios (by RBS and SIMS analyses) and morphology (by AFM and SEM investigations), showing the abundance ratios of such elements in the whole structure. In particular, SIMS maps allowed to study the spatial distribution and thickness of each phase of the Cu-Ti multilayers and further to observe the Cu diffusion and the mixing with Ti, as well as phase separation of CuO and TiO 2 in the samples. This unwanted effect represents an open issue that has to be investigated, in order to improve the MOS fabrication.
Some properties of thermoelectric nano-layers prepared by Pulsed Laser Deposition from hot presse... more Some properties of thermoelectric nano-layers prepared by Pulsed Laser Deposition from hot pressed Bi2Te3 target are presented. The layers were prepared under various deposition conditions that include the substrate temperature during the deposition and the laser beam density, to study its influence on the quality of the surface. Crystallinity, composition and morphology of the layers are presented. Transport and thermoelectric properties such as electrical resistivity, the Seebeck coefficient, power factor and the thermoelectric figure of merit for the smoothest layers prepared at substrate temperature of 200 °C applying laser beam density 3 Jcm-2 are also given. Nano crystallites observed on the layer’s surface are studied by X-ray Diffraction and by Atomic Force Microscope. The problematic of a new method for a relative thermal conductivity characterization of thin thermoelectric layers and multi-layered structures in nanometre range using a scanning thermal microcsope working in...
Phosphorus, Sulfur, and Silicon and the Related Elements, 2020
On the perspective to develop CuO–TiO2 MOS, multilayered Cu and Ti thin layers were alternatively... more On the perspective to develop CuO–TiO2 MOS, multilayered Cu and Ti thin layers were alternatively deposited on silicon wafers using 25 keV Ar + ion beam sputtering and, subsequently, oxidized by thermal annealing in air at 400 °C for 24 h. The deposited films have variable ratios of the Cu and Ti % at. One of the main goal is to obtain such multilayers avoiding the presence of Cu–Ti–O compounds. The samples were characterized in terms of composition (by RBS and SIMS analyses) and morphology (by AFM and SEM investigations). In particular, SIMS maps allows to observe the spatial distribution and thickness of each phase of the Cu/Ti multilayers, and further to observe Cu diffusion and mixing with Ti, as well as phase separation of CuO and TiO2 in the samples. The reasons of this effect represent an open issue that has to investigated, in order to improve the MOS fabrication. GRAPHICAL ABSTRACT
Physica E: Low-dimensional Systems and Nanostructures, 2021
Chemosensors, 2021
Chemiresistors based on thin films of the Li-doped CuO–TiO2 heterojunctions were synthesized by a... more Chemiresistors based on thin films of the Li-doped CuO–TiO2 heterojunctions were synthesized by a 2-step method: (i) repeated ion beam sputtering of the building elements (on the Si substrates and multisensor platforms); and (ii) thermal annealing in flowing air. The structure and composition of the films were analyzed by several methods: Rutherford Backscattering (RBS), Neutron Depth Profiling (NDP), Secondary Ion Mass Spectrometry (SIMS), and Atomic Force Microscopy (AFM), and their sensitivity to gaseous analytes was evaluated using a specific lab-made device operating in a continuous gas flow mode. The obtained results showed that the Li doping significantly increased the sensitivity of the sensors to oxidizing gases, such as NO2, O3, and Cl2, but not to reducing H2. The sensing response of the CuO–TiO2–Li chemiresistors improved with increasing Li content. For the best sensors with about 15% Li atoms, the detection limits were as follows: NO2 → 0.5 ppm, O3 → 10 ppb, and Cl2 → 0...
Crystals, 2019
One dimensional ZnO nanostructures prepared by favorable and simple solution growth methods are a... more One dimensional ZnO nanostructures prepared by favorable and simple solution growth methods are at the forefront of this research. Vertically oriented ZnO nanorods with uniform physical properties require high-quality seed layers with a narrow size distribution of the crystallites, strong c-axis orientation, and low surface roughness and porosity. It has been shown that high quality seed layers can be prepared by the sol–gel process. The sol–gel process involves three essential steps: preparation of the sol, its deposition by dip coating, and thermal treatment comprising preheating and annealing. We put emphasis on the investigation of the heat treatment on the properties of the seed layers and on the vertical alignment of the nanorods. It was demonstrated that for the vertical alignment of the nanorods, the preheating step is crucial and that the temperatures reported in the literature have been too low. With higher preheating temperatures, conditions for the vertical alignment of ...
Applied Physics A, 2016
Thermal conductivity of thermoelectric \hbox {Bi}_{2}\hbox {Te}_{3}$$Bi2Te3 and \hbox {Yb}_{0... more Thermal conductivity of thermoelectric \hbox {Bi}_{2}\hbox {Te}_{3}$$Bi2Te3 and \hbox {Yb}_{0.19}\hbox {Co}_{4}\hbox {Sb}_{12}$$Yb0.19Co4Sb12 thin nanolayers of different thicknesses prepared by pulsed laser deposition on Si (100) substrates was studied by a scanning thermal microscope working in AC current pulse mode. A sensitivity of the approach is demonstrated on the steep Si substrate-layer boundary made by a Ga+ focused ion beam technique. Transport and thermoelectric properties such as in-plane electrical resistivity and the Seebeck coefficient were studied in temperature range from room temperature up to 200\,{}^{\circ }\hbox {C}$$200∘C. The room temperature thermal conductivity of the layers was estimated from thermoelectric figure of merit that was measured by the Harman technique, in which parameters related to electrical conductivity, Seebeck coefficient and thermal conductivity are measured at the same place and at the same time with electrical current flowing through the layer. For \hbox {Yb}_{0.19}\hbox {Co}_{4}\hbox {Sb}_{12}$$Yb0.19Co4Sb12 and \hbox {Bi}_{2}\hbox {Te}_{3}$$Bi2Te3 layers, we observed room temperature electrical resistivity of about 7 and 1\,\hbox {m}\Omega \,\hbox {cm}$$1mΩcm, the Seebeck coefficient of -112$$-112 and -61\,\upmu \hbox {VK}^{-1}$$-61μVK-1, thermoelectric figure of merit about 0.04 and 0.13 and we estimated thermal conductivity of about 1.3 and 0.9\,\hbox {WK}^{-1}\hbox {m}^{-1}$$0.9WK-1m-1, respectively.
Journal of Materials Science and Chemical Engineering, 2016
Thermoelectric layers as Bi 2 Te 3 , Yb 0.19 Co 4 Sb 12 , FeSb 2 Te, Ce 0.1 Fe 0.7 Co 3.3 Sb 12 a... more Thermoelectric layers as Bi 2 Te 3 , Yb 0.19 Co 4 Sb 12 , FeSb 2 Te, Ce 0.1 Fe 0.7 Co 3.3 Sb 12 and FeSb 2 Te/Ce 0.1 Fe 0.7 Co 3.3 Sb 12 multilayers were prepared by Pulsed Laser Deposition (PLD). Smooth, nano-crystalline, stoichiometric layers were synthetized in a classical PLD arrangement or in a special off-axis PLD arrangement, followed by Rapid thermal annealing. Results of physical characterizations such as morphology-Atomic Force Microscope, Scanning Electron Microscope, composition-Energy Dispersive X-ray analysis, crystallinity-X-ray Diffraction, separation of multilayers-Secondary of ion beam mass spectroscopy SIMS and study of thermoelectric properties such as the thermoelectric figure of merit ZT, in-plane electrical resistivity, Seebeck coefficient and thermal conductivity are presented. For thermal conductivity measurement a newly developed Atomic force thermal microscope (AFMTh) was tested. Results obtained on the single layers compared to multi-layered structures are discussed.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000
The structure of the basal plane of a Bi 2 Te 3 crystal surface was studied by means of the atomi... more The structure of the basal plane of a Bi 2 Te 3 crystal surface was studied by means of the atomic force microscopy ͑AFM͒ technique. The measured heights of steps, ranging from 0.2 to 1.4 nm, were in agreement with other structural data of Bi 2 Te 3. The images of freshly cleaved surface, obtained with atomic resolution, revealed a plane of tellurium atoms. The recorded interatomic distances of 0.42Ϯ0.02 nm were also in accordance with the structural data. We also showed that there is a possibility of surface nanostructures formation using the AFM probe, when working above force threshold value.
Journal of Electronic Materials, 2015
We present the development and results of a new simple method for thermal conductivity characteri... more We present the development and results of a new simple method for thermal conductivity characterization of thin films and thermoelectric structures using a scanning thermal microscope in pulsed current mode. The presented method does not allow measurement of absolute thermal conductivity of the studied system, but only relative to the Si substrate. We present the results of the method on the Si substrate/layer step boundary. The nano-layers of different thickness and different materials were prepared for the experiments by the pulsed laser deposition from hot-pressed targets.
Indian journal of experimental biology, 2008
Hypothesis of coherent vibration states in biological systems based on nonlinear interaction betw... more Hypothesis of coherent vibration states in biological systems based on nonlinear interaction between longitudinal elastic and electric polarization fields with metabolic energy supply was formulated by Frohlich. Conditions for excitation of coherent states and generation of electromagnetic fields are satisfied in microtubules which form electrical polar structures. Numerical models are used for analysis of Frohlich's vibration states in cells. Reduction of activity and of energy production in mitochondria, and disintegration of cytoskeleton structures by phosphorylation on the pathway of cancer trasformation can diminish excitation of the Frohlich's vibration states and of the generated electromagnetic field, which results in disturbances of the interaction forces between cells. Interaction forces between cancer cells may be smaller than interaction forces between healthy cells and cancer cells as follows from numerical models. Mechanism of malignity, i.e. local invasion, de...
NATO Science for Peace and Security Series A: Chemistry and Biology, 2014
The properties of very thin Bi2Te3 (nano-) layers of different thickness prepared by pulsed laser... more The properties of very thin Bi2Te3 (nano-) layers of different thickness prepared by pulsed laser deposition at different fluences are presented. Thermoelectric properties such as the thermal conductivity, the in-plain electrical conductivity, the Seebeck coefficient and also crystallinity, composition and morphology are presented. The surface properties were studied by atomic force microscopy.
Proceedings ICT'03. 22nd International Conference on Thermoelectrics (IEEE Cat. No.03TH8726), 2003
Transport properties are presented for 60nm thick layers which were prepared by the laser ablatio... more Transport properties are presented for 60nm thick layers which were prepared by the laser ablation from a Bi2Te3 target. The layers are deposited on quartz glass substrates. The energy density of the laser beam I on the target is 2Jcm-2 and the temperature of the substrate during deposition varies between (200-480°C) for different samples. The influence of the temperature of
Laser Physics, 2014
ABSTRACT A method for relative thermal conductivity characterization of thin thermoelectric layer... more ABSTRACT A method for relative thermal conductivity characterization of thin thermoelectric layers and multi-layered structures in nanometre range using a scanning thermal microscope working in an active constant current mode is suggested. The method requires a very smooth and high quality surface of the studied thermoelectric system. To fulfil these requirements a study of the influence of principal deposition conditions including substrate temperature and laser beam density on surface quality of Bi2Te3 layers prepared by pulsed laser deposition was performed and its results are presented.
2006 25th International Conference on Thermoelectrics, 2006
Bulk Yb0.19Co4Sb12 skutterudite prepared by hot pressing was found to be a good high temperature ... more Bulk Yb0.19Co4Sb12 skutterudite prepared by hot pressing was found to be a good high temperature thermoelectric material with a high figure of merit ZT (ZT=1.2 at T=650 K). In this contribution the properties of thin layers prepared by pulsed laser deposition from such target are presented. The target was prepared by hot pressing and was proved to be a skutterudite
ECS Transactions, 2013
We report on the electrochemical preparation of GaAs porous substrates, their heat treatment in A... more We report on the electrochemical preparation of GaAs porous substrates, their heat treatment in As rich environment and their overgrowth by metalorganic vapor phase epitaxy (MOVPE). The goal is to demonstrate that porous substrates are capable of accommodating strain at the interface with lattice mismatched In(x)Ga(1-x)As layers.
PIERS Online, 2007
Cytoskeleton with microtubules is the main organization structure of the eukaryotic cell. Possibl... more Cytoskeleton with microtubules is the main organization structure of the eukaryotic cell. Possible sources of vibrational excitations of electrically polar cytoskeleton components are enumerated. Temperature stabilized, triple screened box (electrically and electromagnetically by mumetal) with point sensor and preamplifiers was used for measurement of electrical oscillations of yeast cell. Preliminary findings of the electrical measurement and local nanomechanical AFM measurements are presented. Findings correspond to the Frölich's postulate of coherent electrically polar longitudinal vibrations in biological systems.
physica status solidi (c), 2012
We report on the electrochemical preparation of porous GaAs substrates suited for the lattice mis... more We report on the electrochemical preparation of porous GaAs substrates suited for the lattice mismatched epitaxial growth from the liquid and vapour phase The aim is to gain control over the uniformity of the pore nucleation layer and pore branching below this layer to achieve structures with a high degree of porosity and periodicity. The etching process should be surface-friendly and leave minimum damage on the substrate surface to be ready for the subsequent epitaxial growth. We show that surfaces with different pore diameter, pore spacing and surface roughness can be achieved by careful selection of the etching regime, electrolyte, and substrate. Moreover, the pore depth, pore density and pore branching can be tailored to comply with the subsequent epitaxial growth.
Physica E: Low-dimensional Systems and Nanostructures, 2013
ABSTRACT Density of states is studied by a ballistic electron emission microscopy/spectroscopy on... more ABSTRACT Density of states is studied by a ballistic electron emission microscopy/spectroscopy on self-assembled InAs quantum dots embedded in GaAs/AlGaAs heterostructure prepared by metal–organic vapor phase epitaxy. An example of integral quantum dot density of states which is proportional to superposition of a derivative of ballistic current–voltage characteristics measured at every pixel (1.05 nm×1.05 nm) of quantum dot is presented. For the two lowest observed energy levels of quantum dot (the maxima in density of states) the density of states is mapped and correlated with the shape of quantum dot. It was found that prepared quantum dots have a few peaks on their flatter top and a split of the lowest energy level can be observed. This effect can be explained by inhomogeneous (nonuniform) stress distribution in the examined quantum dot.
Journal of Physics: Conference Series, 2014
Multi-layered Ce 0.09 Fe 0.67 Co 3.33 Sb 12 /FeSb 2.1 Te structures composed of thin equidistant ... more Multi-layered Ce 0.09 Fe 0.67 Co 3.33 Sb 12 /FeSb 2.1 Te structures composed of thin equidistant layers were prepared by Pulsed Laser Deposition on fused silica quartz glass substrates. The structures were prepared at different substrate temperatures (230 °C or 250 °C) applying the laser beam energy density of 3 Jcm-2. In the contribution we present some thermoelectric properties such as the in-plane electrical conductivity, the Seebeck coefficient and the power factor for the multi-layered structures in the temperature range from 300 K to 500 K. Comparison of multi-layered structure's thermoelectric properties with single thin Ce 0.09 Fe 0.67 Co 3.33 Sb 12 and FeSb 2.1 Te layers is given. A cross sectional picture of the multilayered structure made by Scanning Electron Microscope is presented for the thicker multilayered structure.