Ivan Kostic | Slovak Academy of Sciences (original) (raw)

Papers by Ivan Kostic

2018 12th International Conference on Advanced Semiconductor Devices and Microsystems (ASDAM), 2018

This study is dedicated to fabrication and characterisation of a Cu20 gas sensor prepared by pote... more This study is dedicated to fabrication and characterisation of a Cu20 gas sensor prepared by potentiostatic electrodeposition on interdigitated electrodes. A new simple and low cost approach based on the overgrowth of IDE fingers by Cu20 layer is used for fabrication of gas sensing structures. Tuning of the deposition charge is shown as a key factor to obtain optimal fingers overgrowth and Cu20 crystals interconnection and hence sensor sensitivity. Comparison of sensors prepared in electrolyte with KOH and LiOR buffers revealed superior sensitivity for the later type. The developed sensor achieved a sensitivity of 3.7 to 1000 ppm of R2 gas measured at 200°C.

Vacuum, 2000

The C layers have been patterned by dry etching. The etch characteristics of this material in var... more The C layers have been patterned by dry etching. The etch characteristics of this material in various etch gases were examined. The carbon structures with high aspect ratio were prepared. The high selectivity between the mask materials and carbon was obtained in H2 and O2.

Thin Solid Films, 2003

High temperature superconductor YBa Cu O (YBCO) and Bi Sr CaCu O (BSCCO) thin film microstrips we... more High temperature superconductor YBa Cu O (YBCO) and Bi Sr CaCu O (BSCCO) thin film microstrips were prepared by 2 3 x 2 2 2 x argon ion beam etching down to a geometrical width W f250 nm. A study of transport properties of the superconducting g microstrips showed that due to the interaction of accelerated argon ions with the superconductor film the edges of microstrips are damaged to a depth DWf85 nm. The effective width of YBCO microstrip W sW y2DWf80 nm is able to transmit a critical ef g current density above 20 MAycm at a temperature of 30 K and a zero external magnetic field. The critical current density of 2 similar BSCCO microstrips was several times smaller.

Superconductor Science and Technology, 2002

ABSTRACT

Review of Scientific Instruments, 2004

... A thick band blinds the reflected ray. Thus the photodetector's output signal is pro... more ... A thick band blinds the reflected ray. Thus the photodetector's output signal is proportional to the total diffracted power for angles smaller than and zero (assuming negligible light background) for the case of TIR. ... E.Moreels, C.deGreef, and R.Finy, “Laser light refractometer,” Appl. ...

Physica C: Superconductivity, 2001

Physica C: Superconductivity, 2006

ABSTRACT

Czechoslovak Journal of Physics, 2004

ABSTRACT

Communications - Scientific letters of the University of Zilina, 2018

Nanometrology is an intrinsic and fast developing part of nanoscience. Given the huge diversity o... more Nanometrology is an intrinsic and fast developing part of nanoscience. Given the huge diversity of nanostructures ranging from large molecules from about 10 atoms to structures from 10 5 atoms (particles of the size ≤ 100 nm), broader investigations in this area cannot be exactly scrutinized nor repeated by the existing capacities. This gave rise to the initiative for reproducibility that aims to avoid simplified approaches, plagiarism and other phenomena that are often triggered by the "publish or perish" philosophy, as well as business practices of predatory journals. In this paper, we discuss two case studies illustrating how to solve these problems: a study of the structural stability of nanoparticles by three complementary methods, and a design of reliable nanoparticle gas sensors used in environment or medicine.

2016 11th International Conference on Advanced Semiconductor Devices & Microsystems (ASDAM), 2016

In this study, a simple patterning method of submicrometer structures is proposed for gas sensor ... more In this study, a simple patterning method of submicrometer structures is proposed for gas sensor development. Comb-like electrodes patterned in thin Pt layer were proposed to measure gas sensor electrical conductivity. Negative resist SU-8 was used as a masking layer for ion etching of electrodes in 35 nm Pt layer on sapphire substrate. This method was applied for the patterning of the comb-like structures with submicrometre dimensions for gas sensor conductivity measurements.

APPLIED PHYSICS OF CONDENSED MATTER (APCOM 2021), 2021

The influence of electron beam lithography parameters (such as electron energy, resist thickness,... more The influence of electron beam lithography parameters (such as electron energy, resist thickness, the exposure dose) on the resist sidewall shape (profile) was studied for the PMMA (polymethyl-methacrylate) positive resist. The profile of the positive tone resist PMMA was investigated depending on varying exposure doses for the resist thicknesses 600 and 1300 nm, and electron energy 30 keV. Simulation results based on measurements along the resist profile depth are presented and discussed. The results obtained contribute to the knowledge on electron scattering in resist/substrate in electron beam lithography for the case of field emission cathode and Gaussian intensity distribution, and to the development and approval of models for the prediction and precise control of resist profiles in thick PMMA layers for 3D proximity effect simulation, the bilayer resist system, and the lift-off method.

Journal of Electrical Engineering, 2021

We present results on very thin NiO films which are able to detect 3 ppm of acetone, toluene and ... more We present results on very thin NiO films which are able to detect 3 ppm of acetone, toluene and n-butyl acetate in synthetic air and to operate at 300°C. NiO films with 25 and 50 nm thicknesses were prepared by dc reactive magnetron sputtering on alumina substrates previously coated by Pt layers as heater and as interdigitated electrodes. Annealed NiO films are indexed to the (fcc) crystalline structure of NiO and their calculated grain sizes are in the range from 22 to 27 nm. Surface morphology of the examined samples was influenced by a rough and compact granular structure of alumina substrate. Nanoporous NiO film is formed by an agglomeration of small grains with different shapes while they are created on every alumina grain.

Journal of Physics: Conference Series, Sep 1, 2018

Journal of Physics: Conference Series, Sep 1, 2018

Journal of Physics: Conference Series, 2018

Experimental and simulation results are presented and discussed on electron-beam lithography (EBL... more Experimental and simulation results are presented and discussed on electron-beam lithography (EBL) nano-structuring using the positive chemically semi-amplified electronbeam resist AR-P 6200 (CSAR 62), which provides high sensitivity and allows achievement of high resolutions (sub-100 nm). The influence of the e-beam lithography process parameters, namely, exposure dose, development process conditions, and proximity effects on the obtained developed images was studied for the case of 40-keV electron energy.

International Journal of Nanomedicine, 2019

Background: Repairs to deep skin wounds continue to be a difficult issue in clinical practice. A ... more Background: Repairs to deep skin wounds continue to be a difficult issue in clinical practice. A promising approach is to fabricate full-thickness skin substitutes with functions closely similar to those of the natural tissue. For many years, a three-dimensional (3D) collagen hydrogel has been considered to provide a physiological 3D environment for cocultivation of skin fibroblasts and keratinocytes. This collagen hydrogel is frequently used for fabricating tissue-engineered skin analogues with fibroblasts embedded inside the hydrogel and keratinocytes cultivated on its surface. Despite its unique biological properties, the collagen hydrogel has insufficient stiffness, with a tendency to collapse under the traction forces generated by the embedded cells. Methods: The aim of our study was to develop a two-layer skin construct consisting of a collagen hydrogel reinforced by a nanofibrous poly-L-lactide (PLLA) membrane pre-seeded with fibroblasts. The attractiveness of the membrane for dermal fibroblasts was enhanced by coating it with a thin nanofibrous fibrin mesh. Results: The fibrin mesh promoted the adhesion, proliferation and migration of the fibroblasts upwards into the collagen hydrogel. Moreover, the fibroblasts spontaneously migrating into the collagen hydrogel showed a lower tendency to contract and shrink the hydrogel by their traction forces. The surface of the collagen was seeded with human dermal keratinocytes. The keratinocytes were able to form a basal layer of highly mitotically-active cells, and a suprabasal layer. Conclusion: The two-layer skin construct based on collagen hydrogel with spontaneously immigrated fibroblasts and reinforced by a fibrin-coated nanofibrous membrane seems to be promising for the construction of full-thickness skin substitute.

Solid State Phenomena, 2003

ABSTRACT

ASDAM 2000. Conference Proceedings. Third International EuroConference on Advanced Semiconductor Devices and Microsystems (Cat. No.00EX386), 2000

A new aqueous base developable, chemically amplified negative resist based on epoxy chemistry (AD... more A new aqueous base developable, chemically amplified negative resist based on epoxy chemistry (ADEPR) is evaluated for high resolution, high-speed e-beam lithography. The acid diffusion coefficient of this system is also evaluated. This resist is formulated using partially hydrogenated poly(hydroxy styrene) and epoxy novolac polymers. The absence of swelling phenomena compared to pure epoxy systems allows lithography up to 100 nm regime and a sensitivity of 4-8 /spl mu/C/cm/sup 2/ at 50 KeV. Both high-resolution line and dot exposures were used in order to evaluate the diffusion coefficient. The value of D=5.10/sup -14/ cm/sup 2//sec fount is a little higher than its pure epoxy counterpart (EPR) but still lower than other commercial resists.

Microelectronic Engineering, 1996

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1998

ABSTRACT The development of stencil masks is considered to be critical to the success of the new ... more ABSTRACT The development of stencil masks is considered to be critical to the success of the new ion projection lithography technology. We present here a p-n junction wafer flow process where all fabrication steps are realized on a bulk Si wafer except the final trench etching through the 2–4-μm-thick Si membrane. Stencil masks were produced in a conventional complementary metal-oxide-semiconductor 150 mm wafer line, using an e-beam direct writing tool for patterning. The resist patterns were transferred by standard reactive ion etching (RIE) into a stress-controlled SiON hard mask layer. Subsequent to depositing an Al metal layer for contact to the n-doped wafer surface, the membrane was realized by a wet chemical etch which implemented well established reverse biased p-n junction etch stop techniques. Then, openings through the Si membrane were etched by RIE or inductively coupled plasma etching. Finally, the remaining hard mask layer was removed in BHF. The realized Si membrane diameter was 120 mm with a stencil pattern field of 60 mm×60 mm. Results from LMS-IPRO placement measurements are in agreement with the simulation of the stencil mask fabrication process using finite element methods. © 1998 American Vacuum Society.

2018 12th International Conference on Advanced Semiconductor Devices and Microsystems (ASDAM), 2018

This study is dedicated to fabrication and characterisation of a Cu20 gas sensor prepared by pote... more This study is dedicated to fabrication and characterisation of a Cu20 gas sensor prepared by potentiostatic electrodeposition on interdigitated electrodes. A new simple and low cost approach based on the overgrowth of IDE fingers by Cu20 layer is used for fabrication of gas sensing structures. Tuning of the deposition charge is shown as a key factor to obtain optimal fingers overgrowth and Cu20 crystals interconnection and hence sensor sensitivity. Comparison of sensors prepared in electrolyte with KOH and LiOR buffers revealed superior sensitivity for the later type. The developed sensor achieved a sensitivity of 3.7 to 1000 ppm of R2 gas measured at 200°C.

Vacuum, 2000

The C layers have been patterned by dry etching. The etch characteristics of this material in var... more The C layers have been patterned by dry etching. The etch characteristics of this material in various etch gases were examined. The carbon structures with high aspect ratio were prepared. The high selectivity between the mask materials and carbon was obtained in H2 and O2.

Thin Solid Films, 2003

High temperature superconductor YBa Cu O (YBCO) and Bi Sr CaCu O (BSCCO) thin film microstrips we... more High temperature superconductor YBa Cu O (YBCO) and Bi Sr CaCu O (BSCCO) thin film microstrips were prepared by 2 3 x 2 2 2 x argon ion beam etching down to a geometrical width W f250 nm. A study of transport properties of the superconducting g microstrips showed that due to the interaction of accelerated argon ions with the superconductor film the edges of microstrips are damaged to a depth DWf85 nm. The effective width of YBCO microstrip W sW y2DWf80 nm is able to transmit a critical ef g current density above 20 MAycm at a temperature of 30 K and a zero external magnetic field. The critical current density of 2 similar BSCCO microstrips was several times smaller.

Superconductor Science and Technology, 2002

ABSTRACT

Review of Scientific Instruments, 2004

... A thick band blinds the reflected ray. Thus the photodetector's output signal is pro... more ... A thick band blinds the reflected ray. Thus the photodetector's output signal is proportional to the total diffracted power for angles smaller than and zero (assuming negligible light background) for the case of TIR. ... E.Moreels, C.deGreef, and R.Finy, “Laser light refractometer,” Appl. ...

Physica C: Superconductivity, 2001

Physica C: Superconductivity, 2006

ABSTRACT

Czechoslovak Journal of Physics, 2004

ABSTRACT

Communications - Scientific letters of the University of Zilina, 2018

Nanometrology is an intrinsic and fast developing part of nanoscience. Given the huge diversity o... more Nanometrology is an intrinsic and fast developing part of nanoscience. Given the huge diversity of nanostructures ranging from large molecules from about 10 atoms to structures from 10 5 atoms (particles of the size ≤ 100 nm), broader investigations in this area cannot be exactly scrutinized nor repeated by the existing capacities. This gave rise to the initiative for reproducibility that aims to avoid simplified approaches, plagiarism and other phenomena that are often triggered by the "publish or perish" philosophy, as well as business practices of predatory journals. In this paper, we discuss two case studies illustrating how to solve these problems: a study of the structural stability of nanoparticles by three complementary methods, and a design of reliable nanoparticle gas sensors used in environment or medicine.

2016 11th International Conference on Advanced Semiconductor Devices & Microsystems (ASDAM), 2016

In this study, a simple patterning method of submicrometer structures is proposed for gas sensor ... more In this study, a simple patterning method of submicrometer structures is proposed for gas sensor development. Comb-like electrodes patterned in thin Pt layer were proposed to measure gas sensor electrical conductivity. Negative resist SU-8 was used as a masking layer for ion etching of electrodes in 35 nm Pt layer on sapphire substrate. This method was applied for the patterning of the comb-like structures with submicrometre dimensions for gas sensor conductivity measurements.

APPLIED PHYSICS OF CONDENSED MATTER (APCOM 2021), 2021

The influence of electron beam lithography parameters (such as electron energy, resist thickness,... more The influence of electron beam lithography parameters (such as electron energy, resist thickness, the exposure dose) on the resist sidewall shape (profile) was studied for the PMMA (polymethyl-methacrylate) positive resist. The profile of the positive tone resist PMMA was investigated depending on varying exposure doses for the resist thicknesses 600 and 1300 nm, and electron energy 30 keV. Simulation results based on measurements along the resist profile depth are presented and discussed. The results obtained contribute to the knowledge on electron scattering in resist/substrate in electron beam lithography for the case of field emission cathode and Gaussian intensity distribution, and to the development and approval of models for the prediction and precise control of resist profiles in thick PMMA layers for 3D proximity effect simulation, the bilayer resist system, and the lift-off method.

Journal of Electrical Engineering, 2021

We present results on very thin NiO films which are able to detect 3 ppm of acetone, toluene and ... more We present results on very thin NiO films which are able to detect 3 ppm of acetone, toluene and n-butyl acetate in synthetic air and to operate at 300°C. NiO films with 25 and 50 nm thicknesses were prepared by dc reactive magnetron sputtering on alumina substrates previously coated by Pt layers as heater and as interdigitated electrodes. Annealed NiO films are indexed to the (fcc) crystalline structure of NiO and their calculated grain sizes are in the range from 22 to 27 nm. Surface morphology of the examined samples was influenced by a rough and compact granular structure of alumina substrate. Nanoporous NiO film is formed by an agglomeration of small grains with different shapes while they are created on every alumina grain.

Journal of Physics: Conference Series, Sep 1, 2018

Journal of Physics: Conference Series, Sep 1, 2018

Journal of Physics: Conference Series, 2018

Experimental and simulation results are presented and discussed on electron-beam lithography (EBL... more Experimental and simulation results are presented and discussed on electron-beam lithography (EBL) nano-structuring using the positive chemically semi-amplified electronbeam resist AR-P 6200 (CSAR 62), which provides high sensitivity and allows achievement of high resolutions (sub-100 nm). The influence of the e-beam lithography process parameters, namely, exposure dose, development process conditions, and proximity effects on the obtained developed images was studied for the case of 40-keV electron energy.

International Journal of Nanomedicine, 2019

Background: Repairs to deep skin wounds continue to be a difficult issue in clinical practice. A ... more Background: Repairs to deep skin wounds continue to be a difficult issue in clinical practice. A promising approach is to fabricate full-thickness skin substitutes with functions closely similar to those of the natural tissue. For many years, a three-dimensional (3D) collagen hydrogel has been considered to provide a physiological 3D environment for cocultivation of skin fibroblasts and keratinocytes. This collagen hydrogel is frequently used for fabricating tissue-engineered skin analogues with fibroblasts embedded inside the hydrogel and keratinocytes cultivated on its surface. Despite its unique biological properties, the collagen hydrogel has insufficient stiffness, with a tendency to collapse under the traction forces generated by the embedded cells. Methods: The aim of our study was to develop a two-layer skin construct consisting of a collagen hydrogel reinforced by a nanofibrous poly-L-lactide (PLLA) membrane pre-seeded with fibroblasts. The attractiveness of the membrane for dermal fibroblasts was enhanced by coating it with a thin nanofibrous fibrin mesh. Results: The fibrin mesh promoted the adhesion, proliferation and migration of the fibroblasts upwards into the collagen hydrogel. Moreover, the fibroblasts spontaneously migrating into the collagen hydrogel showed a lower tendency to contract and shrink the hydrogel by their traction forces. The surface of the collagen was seeded with human dermal keratinocytes. The keratinocytes were able to form a basal layer of highly mitotically-active cells, and a suprabasal layer. Conclusion: The two-layer skin construct based on collagen hydrogel with spontaneously immigrated fibroblasts and reinforced by a fibrin-coated nanofibrous membrane seems to be promising for the construction of full-thickness skin substitute.

Solid State Phenomena, 2003

ABSTRACT

ASDAM 2000. Conference Proceedings. Third International EuroConference on Advanced Semiconductor Devices and Microsystems (Cat. No.00EX386), 2000

A new aqueous base developable, chemically amplified negative resist based on epoxy chemistry (AD... more A new aqueous base developable, chemically amplified negative resist based on epoxy chemistry (ADEPR) is evaluated for high resolution, high-speed e-beam lithography. The acid diffusion coefficient of this system is also evaluated. This resist is formulated using partially hydrogenated poly(hydroxy styrene) and epoxy novolac polymers. The absence of swelling phenomena compared to pure epoxy systems allows lithography up to 100 nm regime and a sensitivity of 4-8 /spl mu/C/cm/sup 2/ at 50 KeV. Both high-resolution line and dot exposures were used in order to evaluate the diffusion coefficient. The value of D=5.10/sup -14/ cm/sup 2//sec fount is a little higher than its pure epoxy counterpart (EPR) but still lower than other commercial resists.

Microelectronic Engineering, 1996

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1998

ABSTRACT The development of stencil masks is considered to be critical to the success of the new ... more ABSTRACT The development of stencil masks is considered to be critical to the success of the new ion projection lithography technology. We present here a p-n junction wafer flow process where all fabrication steps are realized on a bulk Si wafer except the final trench etching through the 2–4-μm-thick Si membrane. Stencil masks were produced in a conventional complementary metal-oxide-semiconductor 150 mm wafer line, using an e-beam direct writing tool for patterning. The resist patterns were transferred by standard reactive ion etching (RIE) into a stress-controlled SiON hard mask layer. Subsequent to depositing an Al metal layer for contact to the n-doped wafer surface, the membrane was realized by a wet chemical etch which implemented well established reverse biased p-n junction etch stop techniques. Then, openings through the Si membrane were etched by RIE or inductively coupled plasma etching. Finally, the remaining hard mask layer was removed in BHF. The realized Si membrane diameter was 120 mm with a stencil pattern field of 60 mm×60 mm. Results from LMS-IPRO placement measurements are in agreement with the simulation of the stencil mask fabrication process using finite element methods. © 1998 American Vacuum Society.