Lidé
Ing. Vojtěch Povolný
Všechny publikace
EVALUATION OF INKJET PRINTED HEATERS ARRAY FOR CHEMO-RESISTIVE GAS SENSOR
- Autoři: Ing. Vojtěch Povolný, Ing. Alexandr Laposa, Ph.D., Ing. Jiří Kroutil, Ph.D., doc. RNDr. Jan Voves, CSc., Ashcheulov, P., prof. Ing. Pavel Hazdra, CSc.,
- Publikace: NANOCON 2023 Conference Proceedings. Ostrava: TANGER, 2024. p. 52-57. NANOCON Conference Proceedings - International Conference on Nanomaterials. ISSN 2694-930X. ISBN 978-80-88365-15-0.
- Rok: 2024
- DOI: 10.37904/nanocon.2023.4770
- Odkaz: https://doi.org/10.37904/nanocon.2023.4770
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
Heaters are an indispensable part of gas sensing platforms. It serves to heat the sensor, which increases the sensitivity of the active layer and helps in the desorption of the detected gas. The sensors are also heated to stabilize the parameters against the ambient temperature. For the fabrication of electronic circuits and devices including sensing platforms and heating structures is becoming increasingly popular to use flexible electronics. In particular, the use of inkjet printing technology allowing localized deposition of ink at low temperatures on a large area. Many kinds of inks such as conductive, semi-conductive, or dielectric can be used. In this research, we present the design preparation, simulation, fabrication, and characterization of the inkjet printed heaters. The structures are based on silver nanoparticle ink printed on a flexible substrate and are sintered with intense pulsed light. The printed heaters consist of connection pads, interconnection pathways, and heater patterns. Two types of heater patterns were designed (meander and dual-spiral type). Both of the prepared patterns were simulated in Ansys simulation software to obtain the heat distribution. The microheaters were printed on a polyethylene terephthalate (PET) substrate and characterized with a thermal imaging camera. Based on the results obtained from these measurements, a calibration plot was created.
Preparation and characterisation of NH3 gas sensor based on PANI/Fe-doped CeO2 nanocomposite
- Autoři: Chakavak Esmaeili, Ph.D., Ashtiani, S., Regmi, Ch., Ing. Alexandr Laposa, Ph.D., doc. RNDr. Jan Voves, CSc., Ing. Jiří Kroutil, Ph.D., Friess, K., Ing. Vojtěch Povolný, Lotfian, S.
- Publikace: Heliyon. 2024, 10(15), 1-12. ISSN 2405-8440.
- Rok: 2024
- DOI: 10.1016/j.heliyon.2024.e34801
- Odkaz: https://doi.org/10.1016/j.heliyon.2024.e34801
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
PANI/Fe-doped CeO2 nanocomposite was synthesised by the in-situ process. The produced powders were characterised by XRD, XPS, FT-IR, Raman, HRTEM and SEM-EDS tests. The sensors' function was based on PANI/Fe-doped CeO2 nanocomposite with thin film deposited on top of interdigitated electrodes (IDT). NH3 detection with PANI/Fe-doped CeO2 nanocomposite sensor could be successfully performed even at room temperature (RT) and relative humidity of 45 %. Results demonstrated that PANI/Fe-doped CeO2 might be promising sensing materials for detecting the low NH3 concentration (ppm). In addition, the sensor is selective to the interfering gases, including CO, CO2 and NO2. This sensor displays acceptable repeatability and stability over time.
Vertical Schottky diode on (113) oriented homoepitaxial diamond
- Autoři: prof. Ing. Pavel Hazdra, CSc., Ing. Alexandr Laposa, Ph.D., Šobáň, Z., Alam, M., Ing. Vojtěch Povolný, Mortet, V.
- Publikace: Diamond and Related Materials. 2024, 146 ISSN 1879-0062.
- Rok: 2024
- DOI: 10.1016/j.diamond.2024.111180
- Odkaz: https://doi.org/10.1016/j.diamond.2024.111180
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
The article presents for the first time vertical Schottky diodes which were fabricated on (113) oriented diamond substrates produced from thick heavily boron-doped diamond layers grown on high-pressure high-temperature grown synthetic Ib diamond crystals. Characteristics of realized diodes, which are fully comparable to those of Schottky-pn diodes prepared on (111) oriented boron-doped diamond, confirm the suitability of (113) orientation for realization of vertical diamond power devices.
Gas Sensor with Different Morphology of PANI Layer
- Autoři: Ing. Jiří Kroutil, Ph.D., Ing. Alexandr Laposa, Ph.D., Ing. Vojtěch Povolný, Klimša, L., prof. Ing. Miroslav Husák, CSc.,
- Publikace: Sensors. 2023, 23(3), 1-14. ISSN 1424-8220.
- Rok: 2023
- DOI: 10.3390/s23031106
- Odkaz: https://doi.org/10.3390/s23031106
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
This work presents the design of a polymer-film-based sensor for gas detection. Different types of polyaniline are used as active layers. The advantages of resistive sensors with PANI layers are easy preparation and low production cost. At room temperature, polymer films have a high sensitivity to gas concentrations. The developed sensor works on the idea of electrical resistance shifting with gas concentration. Three different polymerization solutions are employed to synthesize the polyaniline (PANI) active layers (aqueous solution, sulfuric acid solution, and acetic acid solution). Active layers are evaluated in a controlled environment for their ability to detect ammonia, carbon monoxide, nitrogen monoxide, acetone, toluene, and relative humidity in synthetic air. PANI layers polymerized in acetic acid solutions exhibit good sensitivity toward ammonia.
Power Diode Structures Realized on (113) oriented Boron Doped Diamond
- Autoři: prof. Ing. Pavel Hazdra, CSc., Ing. Alexandr Laposa, Ph.D., Šobáň, Z., Ing. Vojtěch Povolný, doc. RNDr. Jan Voves, CSc., Lambert, N., Taylor, A., Mortet, V.
- Publikace: ISPS'23 PROCEEDINGS. PRaha: České centrum Institution of Engineering and Technology, 2023. p. 69-74. 1. vol. 1. ISBN 978-80-01-07198-4.
- Rok: 2023
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
The article deals with the preparation and characterization of ohmic contacts, pseudo-vertical, and vertical Schottky barrier diodes on (113) oriented boron doped diamond.
Pseudo-vertical Schottky diode with ruthenium contacts on (113) boron-doped homoepitaxial diamond layers
- Autoři: prof. Ing. Pavel Hazdra, CSc., Ing. Alexandr Laposa, Ph.D., Šobáň, Z., Ing. Jiří Kroutil, Ph.D., Lambert, N., Ing. Vojtěch Povolný, Taylor, A., Mortet, V.
- Publikace: PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE. 2023, 220(23), ISSN 1862-6300.
- Rok: 2023
- DOI: 10.1002/pssa.202300508
- Odkaz: https://doi.org/10.1002/pssa.202300508
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
In this article, the electrical properties of pseudo-vertical Schottky barrier diodes (pVSBDs) prepared on (113)–oriented boron-doped diamond layers using ruthenium for both the ohmic and Schottky contacts were investigated.
A chemiresistive sensor array based on polyaniline nanocomposites and machine learning classification
- Autoři: Ing. Jiří Kroutil, Ph.D., Ing. Alexandr Laposa, Ph.D., Ahmad, A., doc. RNDr. Jan Voves, CSc., Ing. Vojtěch Povolný, Klimsa, L., Davydova, M., prof. Ing. Miroslav Husák, CSc.,
- Publikace: Beilstein Journal of Nanotechnology. 2022, 13 411-423. ISSN 2190-4286.
- Rok: 2022
- DOI: 10.3762/bjnano.13.34
- Odkaz: https://doi.org/10.3762/bjnano.13.34
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
The selective detection of ammonia (NH3), nitrogen dioxide (NO2), carbon oxides (CO2 and CO), acetone ((CH3)2CO), and toluene (C6H5CH3) is investigated by means of a gas sensor array based on polyaniline nanocomposites. The array composed by seven different conductive sensors with composite sensing layers are measured and analyzed using machine learning. Statistical tools, such as principal component analysis and linear discriminant analysis, are used as dimensionality reduction methods. Five different classification methods, namely k-nearest neighbors algorithm, support vector machine, random forest, decision tree classifier, and Gaussian process classification (GPC) are compared to evaluate the accuracy of target gas determination. We found the Gaussian process classification model trained on features extracted from the data by principal component analysis to be a highly accurate method reach to 99% of the classification of six different gases.
EVALUATION OF PRINTED INTERDIGITAL ELECTRODES ARRAY FOR CHEMO-RESISTIVE GAS SENSOR APPLICATION
- Autoři: Ing. Vojtěch Povolný, Ing. Alexandr Laposa, Ph.D., Ing. Jiří Kroutil, Ph.D., doc. RNDr. Jan Voves, CSc., Davydova, M., prof. Ing. Pavel Hazdra, CSc.,
- Publikace: NANOCON Conference Proceedings - International Conference on Nanomaterials. Ostrava: TANGER, 2022. p. 45-51. ISSN 2694-930X. ISBN 978-80-88365-09-9.
- Rok: 2022
- DOI: 10.37904/nanocon.2022.4588
- Odkaz: https://doi.org/10.37904/nanocon.2022.4588
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
The article presents the design and preparation of a platform for a gas sensor application based on the ink print of silver nanoparticles on flexible substrates.
Inkjet-printed Mn-Zn ferrite nanoparticle core for fluxgate
- Autoři: Hrakova, D., prof. Ing. Pavel Ripka, CSc., Ing. Alexandr Laposa, Ph.D., Ing. David Novotný, Ing. Jiří Kroutil, Ph.D., Ing. Vojtěch Povolný, Kaman, O., Veverka, P.
- Publikace: Journal of Magnetism and Magnetic Materials. 2022, 563 1-5. ISSN 0304-8853.
- Rok: 2022
- DOI: 10.1016/j.jmmm.2022.170003
- Odkaz: https://doi.org/10.1016/j.jmmm.2022.170003
- Pracoviště: Katedra mikroelektroniky, Katedra měření
-
Anotace:
Non-planar fluxgate sensors measuring the magnetic fields in the uT range are required for electric current, position, and torque transducers. We report the first sensor based on an inkjet-printed 17 mm diameter ring core. The sensor wide open-loop linear range of 1.5 mT allows to operate it without feedback. We describe the preparation of the very stable magnetic ink based on citrate-stabilized 13 nm diameter Mn-Zn ferrite nanoparticles that occur in superparamagnetic regime at room temperature. By printing 100 layers the total thickness of the inkjet-printed core was 2.2 µm. The achieved sensitivity was 10 mV/mT for 25 kHz excitation frequency
Low-resistance ohmic contacts on boron-doped {113} oriented homoepitaxial diamond layers
- Autoři: prof. Ing. Pavel Hazdra, CSc., Ing. Alexandr Laposa, Ph.D., Šobáň, Z., doc. RNDr. Jan Voves, CSc., Lambert, N., Davydova, M., Ing. Vojtěch Povolný, Taylor, A., Mortet, V.
- Publikace: Diamond and Related Materials. 2022, 121 ISSN 0925-9635.
- Rok: 2022
- DOI: 10.1016/j.diamond.2021.108797
- Odkaz: https://doi.org/10.1016/j.diamond.2021.108797
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
Refractory metals (titanium, molybdenum, and zirconium) with a gold overlayer were used to form ohmic contacts on {113}-oriented boron doped diamond epitaxial layers (boron concentration ranging from 1019 to 1021 cm−3). Morphology and thickness of deposited layers were determined by AFM and X-SEM; resistivity, carrier concentration and mobility were determined by Hall measurement. Specific contact resistance RCsp of evaporated Ti/Au, Zr/Au, and Mo/Au contacts was measured using c-TLM structures after different annealing stages at temperatures up to 850 °C. Results show that on layers with {113} orientation it is possible to achieve ohmic contacts of comparable quality as for layers with {100} orientation. For all three metal systems, the lowest values for specific contact resistance reached 1 × 10−6 Ω.cm2. Ti/Au contacts show a stable ohmic behavior over the whole range of annealing temperatures, while Mo/Ti contacts had to be annealed above 500 °C to reduce the Schottky barrier and achieve good ohmic contact on lower B doped layers. Zr/Au contacts exhibit the lowest adhesion and required annealing to at least 700 °C to achieve ideal electrical and mechanical properties. Mo/Au and Zr/Au contacts on highly boron doped layers (~1021 cm−3) show excellent contacts when annealed at 700 °C, and therefore can be considered as improved candidates for ohmic contacts for diamond-based high-temperature power electronics than the conventional Ti/Au (Ti/Pt/Au) contact system. In summary, this study confirms the suitability of {113} oriented boron doped diamond epitaxial layers for the fabrication of diamond power electronic devices with excellent ohmic contacts.
Micro Power Supply Based on Piezoelectric Effect
- Autoři: prof. Ing. Miroslav Husák, CSc., Budková, A., Pýcha, T., Ing. Alexandr Laposa, Ph.D., Ing. Vojtěch Povolný, Ing. Vladimír Janíček, Ph.D., Ing. Jan Novák, Ph.D., Ing. Adam Bouřa, Ph.D., Foit, J.
- Publikace: ASDAM 2022 - The 14th International Conference on Advanced Semiconductor Devices and Microsystems. Bratislava: Slovak Academy of Sciences, Institute of Electrical Engineering, 2022. p. 65-68. ISBN 978-1-6654-6977-7.
- Rok: 2022
- DOI: 10.1109/ASDAM55965.2022.9966775
- Odkaz: https://doi.org/10.1109/ASDAM55965.2022.9966775
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
The paper solves the model of the miniature Power supply based on the piezoelectric cantilever. The aim of the future is to further hybrid integration and use of nanotechnology. Contents of the article belongs to the category of renewable energy sources with environment energy conversion into electrical energy. The work is focused on the use in small temperature differences.
Pseudo-vertical Mo/Au Schottky diodes on {113} oriented boron doped homoepitaxial diamond layers
- Autoři: prof. Ing. Pavel Hazdra, CSc., Ing. Alexandr Laposa, Ph.D., Šobáň, Z., Taylor, A., Lambert, N., Ing. Vojtěch Povolný, Ing. Jiří Kroutil, Ph.D., Gedeonová, Z., Hubík, P., Mortet, V.
- Publikace: Diamond and Related Materials. 2022, 126 ISSN 0925-9635.
- Rok: 2022
- DOI: 10.1016/j.diamond.2022.109088
- Odkaz: https://doi.org/10.1016/j.diamond.2022.109088
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
The article reports for the first time about the successful fabrication of pseudo-vertical diodes on {113} oriented homoepitaxial boron-doped diamond using molybdenum as a metal for both the Schottky and ohmic contacts. Results confirm that the use of {113} oriented homoepitaxial boron-doped diamond for the fabrication of high-temperature power devices is advantageous, as it enables high-quality Schottky and ohmic contacts.
Characterization of the Very Low Contact Resistance on Heavily Boron Doped (113) CVD Diamond
- Autoři: doc. RNDr. Jan Voves, CSc., Ing. Alexandr Laposa, Ph.D., Šobáň, Z., prof. Ing. Pavel Hazdra, CSc., Ing. Vojtěch Povolný, Mortet, V., Lambert, N., Davydova, M.
- Publikace: Nanocon 2021 - ABSTRACTS. Ostrava: TANGER, 2021. p. 47-52. ISBN 978-80-88365-00-6.
- Rok: 2021
- DOI: 10.37904/nanocon.2021.4320
- Odkaz: https://doi.org/10.37904/nanocon.2021.4320
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
The low resistance of ohmic contacts on diamond layers is important for the fabrication of diamond power electronic devices with fast switching capabilities for future high voltage applications. The low barrier height between the metal and diamond, high level of boron doping and annealing at elevated temperatures are the most critical parameters to reach the lowest contact resistivity. In this work, we report on titanium/gold ohmic contacts prepared on the heavily boron-doped (113) epitaxial diamond layers. The contact resistance has been characterized by the Circular Transmission Line Model (cTLM) structures. We used the analytical model of field enhanced emission, tunneling and the image force influence including Fermi level position dependence on the boron concentration for theoretical Ti/Au contact analysis and the Silvaco TCAD 2D simulation to estimate the measurement error associated with the nonzero metal resistance. We show that the resulting simulation values are consistent with the experimental results.
Effect of the substrate crystalline orientation on the surface morphology and boron incorporation into epitaxial diamond layers
- Autoři: doc. RNDr. Jan Voves, CSc., Ing. Alexandr Pošta, Davydova, M., Ing. Alexandr Laposa, Ph.D., Ing. Vojtěch Povolný, prof. Ing. Pavel Hazdra, CSc., Lambert, N., Sedláková, S., Mortet, V.
- Publikace: NANOCON Conference Proceedings - International Conference on Nanomaterials. Ostrava: TANGER, 2021. p. 98-102. ISSN 2694-930X. ISBN 978-80-87294-98-7.
- Rok: 2021
- DOI: 10.37904/nanocon.2020.3683
- Odkaz: https://doi.org/10.37904/nanocon.2020.3683
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
Epitaxial growth of diamond is critically important for the fabrication of diamond-based electronic devices. The emerging study of the epitaxial diamond growth on the (113) vicinal surfaces evidences highly needed high growth rates and low structural defects concentrations with both p- and n-type doping. In this work, we compare the morphology and dopant concentration incorporation of heavily boron-doped (113) epitaxial diamond layers with conventionally studied (100) and (111) epitaxial layers. Epitaxial layers were grown using resonance cavity Microwave Plasma Enhanced Chemical Vapor Deposition (MWPECVD) system. The surface morphology of epitaxial layers was studied by optical microscopy and atomic force microscopy, whereas the boron incorporation homogeneity was determined by Raman spectroscopy mapping. Heavily boron-doped (113) epitaxial diamond layers can be grown at a high growth rate with a smooth surface, without pyramidal hillocks or non-epitaxial crystallite defects, and with homogeneous boron concentration. These results confirm that epitaxial diamond growth on (113) vicinal surfaces is a promising solution for the development and fabrication of diamond-based electronic devices. (9) (PDF) Effect of the substrate crystalline orientation on the surface morphology and boron incorporation into epitaxial diamond layers. Available from: https://www.researchgate.net/publication/349892789_Effect_of_the_substrate_crystalline_orientation_on_the_surface_morphology_and_boron_incorporation_into_epitaxial_diamond_layers [accessed Aug 25 2021].
INKJET PRINTED PASSIVE COMPONENTS
- Autoři: Ing. Vojtěch Povolný,
- Publikace: Proceedings of Student Conference on Sensors, Systems and Measurement 2021. Praha: CESKE VYSOKE UCENI TECHNICKE V PRAZE, 2021. p. 35-36. ISBN 978-80-01-06822-9.
- Rok: 2021
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
Passive components like resistor, capacitor and inductor are basic stones of electrical circuits. Development of these components has come a long way which means that today we can reach very precise values. Inkjet printing is an alternative method how to fabricate electrical components. Inkjet printing has become more popular in recent few years thanks to fast process of fabricating from layout preparation to final product and with effective usage of material it is more efficient and ecological method of fabrication of samples.
Properties of boron-doped (113) oriented homoepitaxial diamond layers
- Autoři: Mortet, V., Taylor, A., Lambert, N., Gedeonová, Z., Fekete, L., Lorinčík, J., Klimša, L., Kopeček, J., Hubík, P., Šobáň, Z., Ing. Alexandr Laposa, Ph.D., Davydova, M., doc. RNDr. Jan Voves, CSc., Ing. Alexandr Pošta, Ing. Vojtěch Povolný, prof. Ing. Pavel Hazdra, CSc.,
- Publikace: Diamond and Related Materials. 2021, 111 ISSN 0925-9635.
- Rok: 2021
- DOI: 10.1016/j.diamond.2020.108223
- Odkaz: https://doi.org/10.1016/j.diamond.2020.108223
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
Although significant efforts have been dedicated to optimize the quality of epitaxial diamond layers, reported properties of diamond based electronic devices do not yet approach expected theoretical values. Recent works indicate that boron-doped and phosphorous-doped diamond can be grown on atomically stepped (113) surfaces (A. Tallaire et al., 2016; M.-A. Pinault-Thaury et al., 2019), however the electrical properties of these layers have not been studied in detail. In this work, we report on structural and electrical properties of boron-doped epitaxial diamond layers grown on (113) substrates. Properties of the diamond layers have been investigated by means of scanning electron microscopy, atomic force microscopy, Hall effect, secondary ion mass spectrometry and Raman spectroscopy. Our results show that boron-doped diamond layers can be grown on (113) substrates at high deposition rates with atomically flat surfaces, excellent electrical properties and high boron incorporation efficiency.
All-Inkjet Printed Flexible Capacitors Utilizing SU-8 and PVP Dielectric Inks
- Autoři: Ing. Vojtěch Povolný, Puci, F.
- Publikace: Proceedings of the International Student Scientific Conference Poster – 23/2019. Praha: ČVUT FEL, Středisko vědecko-technických informací, 2019. p. 87-90. 1. vol. 1. ISBN 978-80-01-06581-5.
- Rok: 2019
- Pracoviště: Katedra mikroelektroniky
-
Anotace:
This paper presents fabrication of printed interdigital capacitors on a flexible and lightweight polyester (PET) substrate. Capacitors were fabricated using inkjet printing technology and conventional low temperature (100-150°C) curing method. The surface of printed capacitors were covered with dielectric material, which lend capacitor a specific value of permittivity, but also serves as protective coating. Cross-linked poly-4- vinylphenol (cPVP) and SU-8 were applied as dielectric materials and experimental results are compared.