Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 29

Number of results on page
first rewind previous Page / 2 next fast forward last

Search results

Search:
in the keywords:  68.35.Ct
help Sort By:

help Limit search:
first rewind previous Page / 2 next fast forward last
1
Content available remote

Gas Sensors Based on ZnO Structures

100%
Struk P., Pustelny T., Gołaszewska K., Borysiewicz M., Piotrowska A.
Acta Physica Polonica A
|
2013
|
vol. 124
|
issue 3
567-569
EN
The paper presents the results of investigations concerning sensor structures based on porous layers of zinc oxide (ZnO) sensitive to a selected gaseous environment. The investigations comprised analyses of the influence of the gaseous environment on the optical properties of a sensor structure, in particularly on the change of the spectral characteristics of optical transmission within the range of ultraviolet light and in the visible range. These presented investigations were carried out in such a gaseous environment as nitrogen dioxide NO_2 in synthetic air.
2
Content available remote

Zinc Oxide Semiconductor for Photonics Structures Applications

100%
Struk P., Pustelny T., Pustelny B., Gołaszewska K., Kamińska E., Piotrowska A., Borysiewicz M., Ekielski M.
|
|
issue 6
1242-1245
EN
The paper presents investigations concerning the analysis of photonic structures with grating couplers. In the paper basic theoretically information on photonic structures with grating couplers is presented. The results of numerical investigations on photonic structures with grating couplers are discussed, too. Investigations show an essential influence of the geometrical parameters of grating couplers on the effectiveness of the input and output of optic power into and out of this photonic structure. In the paper the selected results of experimental realizations of photonic structures with grating couplers based on zinc oxide ZnO are presented.
3
Content available remote

Researches on the Spectral Transmittance of Zinc Oxide ZnO Semiconductor Layers

100%
Struk P., Pustelny T., Opilski Z.
|
|
issue 6
1239-1241
EN
The paper deals with investigations concerning a wide-band gap material, viz. zinc oxide ZnO. Special attention has been devoted to the determination of the spectral transmission of zinc oxide layers deposited on quartz substrates. These investigations have made it possible to determine the optical spectral range in which this material is transparent as well as the edges of absorption. The presented investigations are valuable particularly concerning the application of zinc oxide in optoelectronic and photonic structures as well as in systems of waveguides and sensor layers of integrated optics.
4
Content available remote

Morphology and Stability of the Diamond/BN (001) and (111) Interfaces Based on Ab Initio Studies

100%
Sznajder M., Hrushka N., Majewski J.
Acta Physica Polonica A
|
2016
|
vol. 130
|
issue 5
1220-1223
EN
The morphology, charge distribution and energetic stability of interfaces in the diamond/c-BN heteropolar junctions grown along [001] and [111] crystallographic directions are obtained from first principles calculations in the framework of density functional theory. It turns out that there exist reconstructions of the abrupt interfaces of the C and N adjacent layers (C-N type) that induce charge compensation and lead to the stabilization of the interfaces. On the contrary, our studies strongly suggest that analogous reconstructions of the abrupt interfaces of C and B adjacent layers (C-B type) are not energetically favorable and do not stabilize abrupt interfaces.
5
Content available remote

Effect of the Plasma Deposition Parameters on the Properties of Ti/TiC Multilayers for Hard Coatings Applications

100%
Saoula N., Henda K., Kesri R., Shrivastava S., Erasmus R., Comins J.
Acta Physica Polonica A
|
2012
|
vol. 121
|
issue 1
172-174
EN
Titanium carbide (TiC) hard coatings have been obtained on steel and silicon substrates by rf magnetron sputtering process. Two layer coatings have been deposited in order to improve adhesion on steel. The lower layer was titanium metal and the upper TiC layer was obtained by reactive sputtering of the titanium target in Ar and methane gas mixture. The study confirmed that the TiC layer composition depends on the reactive sputtering gas composition and substrate bias voltage. Film microhardness was measured by microindentation. Measurement results showed that the hardness coating depends on the microstructure of our coatings and the polarization of bias substrate is an important parameter to control the microstructure.
6
Content available remote

Observation and Control of Interfacial Defects in ZnO/ZnSe Coaxial Nanowires

100%
Bhutto W., Wu Z., Cao Y., Wang W., Kang J.
|
|
vol. 125
|
issue 4
994-996
EN
ZnO/ZnSe coaxial nanowires with different ZnO core diameters were synthesized by using a two-step chemical vapor deposition. The scanning electron microscopy images demonstrated that the coaxial nanowires with small ZnO core diameter had the smoother surface than that with large ZnO core diameter. A coherent ZnSe layer with wurtzite structure was observed in the nanowire interface between the ZnO core and the ZnSe shell by high resolution transmission electron microscopy. This coherent layer is beneficial to reduce the defect density and improve the crystal quality by suppressing the phase transition. It was found that the coherent thickness was significantly related to the ZnO core diameter. For the nanowire with large ZnO core, a thin critical thickness of 2 - 3 nm was obtained. As a result, a layer of zinc blende ZnSe appeared outside the nanowire, and a lot of defects existed in the interface between the ZnSe layers with different phase structures. For the nanowire with small ZnO core, however, the critical thickness increased and a coherent coaxial structure was observed with the same lattice spacing in the ZnO core and the ZnSe shell. To obtain defect-free coaxial nanowire, an optimal structure was also proposed by theoretical calculation.
7
Content available remote

Synthesis of Super Hydrophobic Clay by Solution Intercalation Method from Aqueous Dispersions

100%
Acikyildiz M., Gurses A., Yolcu H.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 4
1156-1160
EN
The super hydrophobic materials have inspired a great deal of interest and research in recent years because of their unique water-repellent, self-cleaning properties, and their potential for practical applications. This study aims to create a super hydrophobic clay surface from aqueous dispersions of a long-chain hydrocarbon, Cetyltrimethylammonium Bromide (CTAB), and layered silicate via the solution intercalation method. First, to increase diffusing tendency of CTA^{+ }ions from aqueous medium to the interlayer region of clay, long-chain hydrocarbon agent was dispersed in aqueous surfactant solution via hydrophobic interactions between the tails of CTA^{+} ions and hydrocarbon chains. Then, the adsorption of the long tailed ions of CTAB on the surface of the clay layers was carried out. Effects of variables, such as temperature, initial surfactant concentration and hydrocarbon dosage onto the adsorbed amount of CTA^{+} ions were investigated by considering the zeta potentials and contact angle values of organo-clay particles. The results show that by intercalation of the long tailed CTA^{+} ions to the interlayer galleries of clay, high hydrophilic clay can be possible to convert to super hydrophobic clay. Also, the static contact angle values of organo-clay particles progressively increase with the increasing amount of hydrocarbon. The static contact angle value of powder organo-clay is about 150°, indicating its super hydrophobic character. XRD pattern and HRTEM images for the organo-clay confirm the intercalated structures.
8
Content available remote

Interface Properties of Single and Bi-Layer Fe_3O_4 Films Grown on MgO(001) Studied by RBS and Channeling Experiments

100%
Kim-Ngan N., Balogh A., Brötz J., Zając M., Korecki J.
|
|
issue 4
570-575
EN
Series of Fe_3O_4/MgO(001) and Fe_3O_4/Fe/MgO(001) films (single- and bi-layer films, respectively) with a total layer thickness in the range of 20 ÷ 150 nm were investigated by the Rutherford backscattering spectrometry (2 MeV He^{+} ion beam), by the Rutherford backscattering spectrometry channeling experiments (1.5 MeV He^{+} ion beam). Depending on the layer thickness of each layer and the film geometry, a single Fe peak and/or a double-anomaly feature was revealed in the Rutherford backscattering spectra. For all films no magnesium presence in the surface layer was observed. For both single- and bi-layer films with a total layer thickness less than 60 nm only one minimum was observed in the channeling curves, while a double minimum was revealed for the bi-layer films with a larger thickness. X-ray reflectometry measurements have revealed that the film density is the same as that of the bulk one.
9
Publication available in full text mode
Content available

Annealing Study of Al/GaSb Contact with the Use of Doppler Broadening Technique

100%
Wang H., Weng H., Ling C., Ye B., Zhou X., Han R.
Acta Physica Polonica A
|
2005
|
vol. 107
|
issue 5
874-879
EN
Using a monoenergetic positron beam, annealing study of the Al/n-GaSb system was performed by monitoring the Doppler broadening of the annihilation radiation as a function of the positron implanting energy. The S-parameter against positron energy data was successfully fitted by a three-layer model (Al/interface/GaSb). The annealing out of the open volume defects in the polycrystalline Al layer was revealed by the decrease in the S-parameter and the increase in the effective diffusion length of the Al layer. For the as-deposited samples, a 5 nm interfacial region with S-parameter larger than those of the Al overlayer and the bulk was identified. After the 400ºC annealing, this interfacial region extends to over 40 nm and its S-parameter dramatically drops. This is possibly due to the new phase formation at the interface. Annealing behaviors of S_B and L_{+,B} of the GaSb bulk showed the annealing out of positron traps (possibly the V_{Ga}-related defect) at 250ºC. However, a further annealing at 400ºC induces the formation of positron traps, which are possibly of another kind of V_{Ga}-related defect and the positron shallow trap GaSb antisite.
10
Content available remote

Structure and Charge Compensation of Heteropolar SiC/GaN Interfaces

100%
Sznajder M., Majewski J.
Acta Physica Polonica A
|
2013
|
vol. 124
|
issue 5
772-774
EN
We present studies of the morphology and charge distribution at the 4H-SiC/wz-GaN heteropolar junctions. Our investigations are based on the first principles calculations in the framework of the density functional theory where the interfaces between the SiC substrate and GaN layers are represented by means of a slab. These studies reveal possible charge compensation patterns at the interfaces that lead to charge redistribution from monopole to dipole character and increase the stability of the junctions. It turns out that the interfaces with C-Ga and Si-Ga bonds across the junction and reconstructions involving substitution of group IV elements into Ga layer are the most favorable energetically.
11
Content available remote

Surface Modifications of a Ti6Al4V Alloy by a Laser Shock Processing

100%
Rozmus-Górnikowska M.
|
|
issue 5
808-811
EN
The influence of the Laser Shock Processing (LSP) on the morphology, microstructure and surface layer properties of a Ti6Al4V alloy has been studied. Residual stresses were assessed as well. For the Laser Shock Processing a 1 KW, high-power Q-switched Nd:YAG laser was used. During the process the surface of the investigated material was covered by series of single, partially overlapping impulses. The laser power density was a 1 GW/cm^{2} and a pulse duration of 18 ns. The microstructure and the phases presented in the surface layer of the treated material were analysed by optical, scanning and transmisssion electron microscopy as well as by X-ray diffractometry. The X-ray diffractometry was also use to determine the residual stresses. It has been found that the laser shock processing can cause plastic deformation and generate the compressive residual stresses into the treated surface of a Ti6Al4V alloy.
12
Content available remote

Ellipsometric Measurements of Plastically Deformed Copper

100%
Mirić M., Rudolf R., Anžel I., Hadžić B., Romčević M., Trajić J., Romčević N.
Acta Physica Polonica A
|
2009
|
vol. 116
|
issue 4
715-717
EN
Chemically pure copper (99.99) prepared in the sample of square cross-section (10×10 mm^{2}) and length about 50 mm was extremely plastically deformed with the repeated application of equal channel angular pressing. Equal channel angular pressing was applied as an effective technique for producing bulk nanoscaled structures. It is well known that severe plastic deformation of metallic materials often leads to microstructure with ultrafine grains and cross-sections which remain about equal before and after deformation. Optical properties of the sample were studied using spectroscopic ellipsometry in UV-VIS range. The parameters of the sample like copper oxide and surface roughness overlayer were calculated using two-film model together with the Bruggeman effective medium approximation.
13
Content available remote

Dielectric Function of Nitride Semiconductors: Recent Experimental Results

100%
Goldhahn R.
Acta Physica Polonica A
|
2003
|
vol. 104
|
issue 2
123-147
EN
A review on the experimental determination of the dielectric function for hexagonal nitride semiconductors is presented. The peculiarities of nitride samples such as surface roughness and extended interface layers alter in comparison to an ideal film spectroscopic ellipsometry or reflectance spectra in a characteristic manner. It requires the application of multi-layer models for data analysis in order to determine reliable dielectric functions. Results of such an analysis for GaN covering a broad spectral range are given. Below the band gap, both ordinary and extraordinary components of the dielectric function tensor are determined for GaN as well as for AlN. The dielectric functions of MBE-grown InN characterised by a band gap of around 0.75 eV and a sputtered film exhibiting an absorption edge of around 1.9 eV are compared with results of first-principles calculations. Good agreement between theory and experiment is only found for the MBE-grown material providing further evidence that InN is a "narrow" band gap semiconductor. Finally, photocurrent measurements of a GaN Schottky-diode reveal the influence of electric fields on the shape of the excitonic absorption edge. The interpretation is supported by results of dielectric function calculations.
14
Content available remote

Thermal Modelling of Quantum Cascade Lasers

100%
Spagnolo V., Vitiello M., Di Franco C., Scamarcio G.
Acta Physica Polonica A
|
2009
|
vol. 116
|
issue 4
451-454
EN
One of the top priorities in the development of quantum cascade laser sources is the optimization of the heat transport dynamic. We review here our experimental studies on the thermal properties of state of art quantum cascade lasers operating both in the mid-IR and THz ranges. The experimental approach is based on the investigation of the band-to-band photoluminescence signals, collected during device continuous wave operation. We measured the lattice temperature profile on the device front facet and using these data as inputs, we extract the heat dissipation patterns, the in-plane and the cross-plane active region thermal conductivities and the thermal boundary resistance for quantum cascade lasers based on different material systems.
15
Content available remote

Effect of Interface Roughness on Resonant Tunnelling in Double-Barrier Heterostructures

100%
Figielski T., Wosiński T., Mąkosa A.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 4
777-780
EN
We argue that the well-boundary roughness in a double-barrier heterostructure induces subsidiary subbands in the quantum well which, in turn, lead to the appearance of a broad shoulder beyond the principal resonance peak in the current-voltage characteristics.
16
Content available remote

Morphology and Stability of the C/BN Interfaces: Ab Initio Studies

100%
Grabowski M., Sznajder M., Majewski J.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 1a
A-138-A-141
EN
We investigate the morphology and charge distribution at the (001)-diamond/BN heteropolar junctions of the cubic materials. Our investigations are based on the first principles calculations in the framework of the density functional theory. These studies reveal that reconstruction of the interface leads to possible charge compensation at the interface and increases also the stability of the junction in comparison to the abrupt interfaces.
17
Content available remote

Wetting of Nanostructurized Sapphire and Gold Surfaces

100%
Kempiński M., Jenczyk J., Jurga S., Śliwińska-Bartkowiak M.
|
EN
We present the results of preliminary experiments regarding research on the contact angle measurements of various liquids on solid surfaces with different morphology. The aim was to get insight into the dependence of wetting phenomena on the nanoscale surface roughness. Flat and nanostructurized surfaces of gold and sapphire were used in the experiments. Four liquids - bromobenzene, water, mercury, and gallium - covering a broad range of surface tension values were used to check how varying roughness influences wetting in the systems with different adhesion/cohesion ratio. Structurization was anisotropic, which resulted in the very interesting behaviour of the examined liquids on the selected surfaces. Significant change of the wetting properties was observed as well as a strong dependence on the surface morphology.
18
Content available remote

Work Function of Vicinal Copper Surfaces

100%
Godowski P., Onsgaard J.
Acta Physica Polonica A
|
2013
|
vol. 123
|
issue 1
115-117
EN
Relative work functions of vicinal surfaces to the (100) plane copper surface were determined from the Δ ϕ changes during adsorption of potassium. The initial value of the work function of the different planes was determined from its saturation value under the condition that it corresponds to the potassium overlayer of the same structure and density. It was found that the work function decreases linearly with step density for this step orientation.
19
Publication available in full text mode
Content available

Investigation of Nanocrystalline Materials by Perturbed Angular Correlation and Supplementing Experimental Techniques

88%
Wolf H.
Acta Physica Polonica A
|
2006
|
vol. 109
|
issue 3
433-440
EN
Nanocrystalline materials were investigated by perturbedγγ-angular correlation using the radioactive probe ^{111}In. For identifying local structures observed by perturbedγγ-angular correlation various supplementing experimental techniques, like X-ray diffraction, transmission electron microscopy, absorption spectroscopy, and photoluminescence spectroscopy, were applied. In nanocrystalline TiAl alloys different crystallographic structures were observed depending on the conditions of sample treatment. Nanocrystalline Ni samples show a slightly modified local magnetic field in regions adjacent to the grain boundaries. In addition, ordered grain boundary structures were observed. Ni precipitates were identified in nanocrystalline NiCu alloys by perturbed γγ-angular correlation and preparation conditions avoiding these precipitates were found. For nanocrystalline ZnO preparation conditions were found yielding In-doped particles of good crystalline quality.
20
Content available remote

Surface Morphology Analysis of Composite Thin Films based on Titanium-Dioxide Nanoparticles

88%
Ţălu Ş., Bramowicz M., Kulesza S., Pignatelli F., Salerno M.
Acta Physica Polonica A
|
2017
|
vol. 131
|
issue 6
1529-1533
EN
This study addressed the advanced micro-morphological characterization of 3D surfaces of thin films based on composites of an organic matrix of poly-methyl-methacrylate and inorganic titanium-dioxide nanocrystals. The films were prepared by spin-coating of a series of solutions with increasing loading concentration of the nanocrystals, from 5 up to 40% by weight. The film surfaces were investigated by atomic force microscopy, and the resulting images were analyzed in detail to obtain a full quantitative description of their surface micro-morphology. The fractal analysis of the surface roughness was used to extract the characteristics of amplitude, spatial distribution, and pattern. A fractal geometry was indeed observed, and the corresponding fractal dimension D was determined for all the samples. In view of the possible use of these thin films as functional coatings, the calculated quantities are discussed with respect to the foreseen durability of these surfaces during operation under wear.
first rewind previous Page / 2 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.