Ákos Nemcsics

55925750900

Publications - 8

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

Plausible quantum-mechanical interpretations of RHEED oscillation

Ákos Nemcsics Szilvia Nagy

Publication Name: Vacuum

Publication Date: 2012-01-27

Volume: 86

Issue: 6

Page Range: 620-622

Description:

In this paper the oscillations of reflection high-energy electron diffraction is investigated on the basis of the electron complementarity principle and quantum entanglement. The intensity oscillations during the growth process can be explained by the change of the surface morphology, which is caused by the changing of the experimental conditions. The experimental conditions affect both the description of the interaction on the surface and the behavior of the electrons as quantum mechanical entities, i.e., if their particle-like or wave-like properties dominate. The interpretation of these phenomena can be made plausible with the help of the idea of quantum entanglement. © 2011 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2011.07.020

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

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