Antal Ürmös

57190213039

Publications - 5

Contact problems in GaAs-based solar cells

Ákos Nemcsics Antal Ürmös Zoltán Farkas L. Dobos Szilvia Nagy

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2018-01-01

Volume: 15

Issue: 6

Page Range: 99-124

Description:

The present work deals with contact problems of GaAs-based solar cells. In the introduction the most basic GaAs-based solar cell structures are introduced. Then, the energy and electronic properties are investigated. In the third part of this publication, the technological aspects of the metallization are discussed. Here the surface patterns are investigated, that are formed at the surface of the Au/GaAs and Au/TiN/GaAs material systems, as the effect of the annealing process. The further aim of these investigations to investigate, how the properties of ohmic contact depends on the properties of the material system. If these relations are known, the relationships between different morphologies and their electric qualities will be also known.

Open Access: Yes

DOI: 10.12700/APH.15.6.2018.6.6

Fuzzy and Kohonen SOM based classification of different 0D nanostructures

Mark Farkas Ákos Nemcsics Antal Ürmös Zoltán Farkas Tamás Sándor L. T. Koczy

Publication Name: Sami 2017 IEEE 15th International Symposium on Applied Machine Intelligence and Informatics Proceedings

Publication Date: 2017-03-16

Volume: Unknown

Issue: Unknown

Page Range: 365-370

Description:

In this paper, the clustering of the GaAs-based droplet epitaxially grown self-assembled nanostructures was investigated by soft-computing methods. The properties and the operation of these devices, depend on the type, the shape, the size, and their distribution of these 0 dimensional nanostructures. Because of this, it is very important to know, how and what kind of nanostructures can form, at the given technological parameters. Our goal is the classification of these nanostructures, in order to support the research and the production of these devices. Our solution is based on the shape factor calculation of the given nanostructure. In this work, two possible classification methods of nanostructures were introduced as well. First, the classification potential of the Kohonen Self-Organizing Mapping (SOM) was investigated. Second, the fuzzy inference system based classification was studied. In this case, the shape factor was determined by geometrical sizes of the nanostructures. In this paper the clustering was introduced, which supports many kinds of technology as well.

Open Access: Yes

DOI: 10.1109/SAMI.2017.7880335

Application of self-organizing maps for technological support of droplet epitaxy

Mark Farkas Ákos Nemcsics Antal Ürmös Zoltán Farkas Tamás Sándor L. T. Koczy

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2017-01-01

Volume: 14

Issue: 4

Page Range: 207-224

Description:

The subject of this paper is the self-organized grouping of droplet epitaxial III-V-based nano-structures. For the nano-structure grouping, our developed algorithm - called Quantum Structure Analyzer 1.0 - is used. The operation of this software is based on the principles of the Kohonen Self-Organizing Network. Here, three possibilities for nano-structured groupings are shown. On one hand, we examine the classification of nanostructures with Kohonen Self-Organizing Maps, on the other hand, fuzzy inference systems are applied for the same goal. In the case of the fuzzy methods two approaches are examined in detail. According to the first fuzzy inference approach, the shape factor is calculated from the size of nanostructures. According to the second fuzzy inference approach, the shape factor calculation is based on the controllable parameters of the growth process (eg. pressure and the temperature of the substrate).

Open Access: Yes

DOI: 10.12700/APH.14.4.2017.4.12

Quantum structure classification by Kohonen Self-Organizing Map and by Fuzzy C-Means algorithm

Mark Farkas Ákos Nemcsics Antal Ürmös L. T. Koczy

Publication Name: Icsse 2013 IEEE International Conference on System Science and Engineering Proceedings

Publication Date: 2013-11-18

Volume: Unknown

Issue: Unknown

Page Range: 313-318

Description:

Nowadays the nanostructures, formed on the way of self assembly are intensively investigated both in the basic and the applied sciences. In our paper, we investigate the structures on III-V compund semiconductor based materials, which are grown by epitaxial process. This process is analized by the beta version of Quantum Structure Analyzer 1.0, which is developed in C# langague, in the Microsoft© Visual Studio 2008 development environment. This software operates with the help of the Kohonen Self-Organizing Maps (SOM) algorithm and with the help of the Fuzzy C-Means algorithm. In present work, in the preface we give a short introduction of Molecular Beam Epitaxy (MBE), after this we introduce the algorithms, applied in this software. Finally, we demonstrate the results of the program. © 2013 IEEE.

Open Access: Yes

DOI: 10.1109/ICSSE.2013.6614682

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