I. Mojzes

7004147768

Publications - 8

Fractal and structural entropy calculations on the epitaxially grown fulleren structures with the help of image processing

Péter Turmezei Ákos Nemcsics I. Mojzes Szilvia Nagy

Publication Name: Sisy 2009 7th International Symposium on Intelligent Systems and Informatics

Publication Date: 2009-12-01

Volume: Unknown

Issue: Unknown

Page Range: 65-67

Description:

Molecular beam epitaxially grown fullerene layers are investigated with the help of image processing. The layered structures are studied in morphological respect. The individual layer morphologies are derived from the atomic force microscopy picture of the surface. The pattern morphology of the certain layers is analysed by box counting method. The surface morphology shows fractal behaviour. The pattern of each layer shows different dimension. The actual dimension depends on the actual distance of the layer from the substrate. The change of the dimension is attributed to the change of the binding behaviour. The topology of the surface is also studied using participation ratio and structural entropy calculations. © 2009 IEEE.

Open Access: Yes

DOI: 10.1109/SISY.2009.5291194

Fractal properties of gold, palladium and gold-palladium thin films on InP

Antal Ürmös Bernadett Varga I. Mojzes Szilvia Nagy

Publication Name: Vacuum

Publication Date: 2009-08-25

Volume: 84

Issue: 1

Page Range: 247-250

Description:

Thermal interaction of indium phosphide (InP) bulk compound semiconductor with thin gold metal films was investigated in the course of the present work. The interaction of the InP/Au system resulted in a pattern showing fractal dimensions. The temperature dependence of the fractal parameters was investigated in a broad temperature range from 200 to 600 °C. No significant temperature dependence of the fractal dimension was observed. The same calculations will be presented for Au/InP and AuPd/InP systems. Our calculations show that the Pd-based contacts have a different behaviour than AuGe metallization where a strong temperature dependence of the fractal number was observed earlier. Another topology measure, the structural entropy is also calculated for the samples. The structural entropy is usually applied for determining the type of the localization of charge distributions, but it can also be used for generalized charges, such as the lightness of the pixels of an electron microscopy picture. © 2009 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2009.06.004

Structural entropy in detecting background patterns of AFM images

László Milán Molnár I. Mojzes Szilvia Nagy

Publication Name: Vacuum

Publication Date: 2009-08-25

Volume: 84

Issue: 1

Page Range: 179-183

Description:

Structural entropy was developed for detecting the type of localization in charge distributions on a finite grid, especially in mesoscopic electronic systems. However, it is possible to detect and analyze superstructures, i.e., topologies consisting of more structures with different types of localization properties. In the definition of the structural entropy, the von Neumann entropy of the system is divided into two parts: first, the extension entropy, which is simply the logarithm of the occupation number; the second part is the structural entropy. On a structural entropy versus logarithm of the spatial filling factor map, the different types of localizations follow different, well-characterized curves. Spatial filling factor measures the percentage of the "filled" (i.e., high intensity) pixels of the image. An atomic force microscopy (AFM) image can be interpreted as some kind of charge distribution on a grid: after normalization, the darkness (or lightness) of the pixels fulfills all the necessary conditions. AFM image artifacts can be detected by plotting the structural entropy versus the logarithm of the spatial filling factor maps of the images. Not only the type of an added large-scale Gaussian, parabolic, exponential, or other function can be identified, but also by careful study of the curves belonging to the structures, the parameters can be detected, too. © 2009 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2009.04.025

Fractal properties of AlGeNi layers on GaAs surfaces

László Milán Molnár Bernadett Varga I. Mojzes Szilvia Nagy

Publication Name: Vacuum

Publication Date: 2009-08-25

Volume: 84

Issue: 1

Page Range: 251-253

Description:

The thermal interactions of thin AlGe and AlNiGe layers with a bulk GaAs monocrystal were investigated. The heat treatment of these systems was carried out in the working chamber of a scanning electron microscope. The SEM pictures were analysed using a fractal mathematical technique. It was found that the surface of the samples has fractal character. No temperature dependence of the fractal dimension was observed. The samples were also studied using the structural entropy versus filling factor maps of the samples in order to find their localization properties. The SEM pictures of AlGe perform mostly as a Gaussian functions, whereas the AlNiGe samples show usually a behaviour with exponential decay. © 2009 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2009.06.005

Investigation of the surface morphology on epitaxially grown fullerene structures

Ákos Nemcsics R. Adelung I. Mojzes L. Kipp Szilvia Nagy S. Woedtke R. Schwedhelm

Publication Name: Vacuum

Publication Date: 2009-08-25

Volume: 84

Issue: 1

Page Range: 152-154

Description:

Fullerene layers molecular beam epitaxially grown on, a vanadium-selenide substrate are investigated and the morphology of the layered structures is studied. The individual layer morphologies are derived from the atomic force microscopy picture of the surface. The pattern morphology of certain layers is analyzed by a box counting method. The surface morphology shows fractal behaviour. The pattern of each layer shows different dimensions. The actual dimension depends on the actual distance of the layer from the substrate. The change of the dimension is attributed to the change of the binding behaviour. The topology of the surface is also studied using participation ratio and structural entropy calculations. © 2009 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2009.04.060

Some remarks to the nanowires grown on III-V substrate

Ákos Nemcsics László Milán Molnár I. Mojzes Zsolt J. Horváth Szilvia Nagy Eniko Horváth

Publication Name: Asdam 2008 Conference Proceedings of the 7th International Conference on Advanced Semiconductor Devices and Microsystems

Publication Date: 2008-12-01

Volume: Unknown

Issue: Unknown

Page Range: 215-218

Description:

In the present work nanowires are investigated, which were prepared with the help of encapsulated metal induced growth method on GaAs and InP substrate. As our former investigations how, we can receive nanowires with substrate-like composition in the case of InP. In the case of GaAs substrate the situation is entirely different, while the growth technology in both cases was the same. The difference between the nanoproducts in the cases of different substrates originate in the reactivity of the components, which is explained in the following considerations. Furthermore we have observed that the diameter of the nanowires depends on the electron energy of the irradiation. If the electron beam was 5 kV and 20 kV, the diameter lasting increases and decreases, respectively. This effect can be explained by the change of the nanowires structure influenced by the electron beam. © 2008 IEEE.

Open Access: Yes

DOI: 10.1109/ASDAM.2008.4743320

Heat treatment parameters effecting the fractal dimensions of AuGe metallization on GaAs

Csaba Dominkovics János Pipek L. Dobos Gábor Harsányi I. Mojzes Szilvia Nagy

Publication Name: Applied Physics Letters

Publication Date: 2007-08-24

Volume: 91

Issue: 7

Page Range: Unknown

Description:

Correlation was detected between the thermal treatment parameters of the AuGe-GaAs system and surface fractal structure. Structural entropic calculations were used to confirm the results obtained by fractal calculations. © 2007 American Institute of Physics.

Open Access: Yes

DOI: 10.1063/1.2768911

Analysis of morphology changes of heat treated metallization of compound semiconductors by the fast wavelet-transform based on B-Spline

K. A. Demcu M. Schusztera L. Dobos I. Mojzes Szilvia Nagy

Publication Name: Journal of Optoelectronics and Advanced Materials

Publication Date: 2007-01-01

Volume: 9

Issue: 7

Page Range: 2241-2244

Description:

Heat treatment of metallized compound semiconductors results in generation of Ohmic contacts. The morphology changes of the surface during the thermal treatment can be observed by scanning electron microscope. According to our previous results these patterns show fractal character. The fractal dimension of a self-similar object can be calculated using the toolbox of fast wavelet-transform. A method is presented for analyzing the electron microscopic images of the heat treated samples by a fast wavelet-transform based algorithm using the filter coefficients of the two dimensional B-Spline functions. A connection between the dimension values of the patterns and the temperatures of the heat treating are shown.

Open Access: Yes

DOI: DOI not available