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207 results on '"Remes, Z."'

12. Substrate temperature changes during MBE growth of GaMnAs

Author

Novak, V., Olejnik, K., Cukr, M., Smrcka, L., Remes, Z., and Oswald, J.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Other Condensed Matter
Abstract

Remarkably big increase of the substrate temperature during the low-temperature MBE growth of GaMnAs layers is observed by means of band gap spectroscopy. It is explained and simulated in terms of changes in the absorption/emission characteristics of the growing layer. Options for the temperature variation damping are discussed., Comment: 5 pages, 5 figures Submitted to Journal of Applied Physics

Published
2007
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33. Optical characterization of poly-SiOx and poly-SiCx carrier-selective passivating contacts

Author

Singh, M. (author), Santbergen, R. (author), Mazzarella, L. (author), Madrampazakis, A. (author), Yang, G. (author), Vismara, R. (author), Remes, Z. (author), Weeber, A.W. (author), Zeman, M. (author), Isabella, O. (author), Singh, M. (author), Santbergen, R. (author), Mazzarella, L. (author), Madrampazakis, A. (author), Yang, G. (author), Vismara, R. (author), Remes, Z. (author), Weeber, A.W. (author), Zeman, M. (author), and Isabella, O. (author)

Abstract

The optical modelling for optimizing high-efficiency c-Si solar cells endowed with poly-SiOx or poly-SiCx carrier-selective passivating contacts (CSPCs) demands a thorough understanding of their optical properties, especially their absorption coefficient. Due to the mixed phase nature of these CSPCs, spectroscopic ellipsometry is unable to accurately detect the weak free carrier absorption (FCA) at long wavelengths. In this work, the absorption coefficient of doped poly-SiOx and poly-SiCx layers as function of oxygen and carbon content, respectively, was obtained for wavelengths (300–2000 nm) by means of two alternative techniques. The first approach, photothermal deflection spectroscopy (PDS), was used for layers grown on quartz substrates and is appealing from the point of view of sample fabrication. The second, a novel inverse modelling (IM) approach based on reflectance and transmittance measurements, was instead used for layers grown on textured c-Si wafer substrates to mimic symmetrical samples. Although the absorption coefficients obtained from these two techniques slightly differ due to the different used substrates, we could successfully measure weak FCA in our CSPCs layers. Using an in-house developed multi-optical regime simulator and comparing modelled reflectance and transmittance with measured counterparts from symmetrical samples, we confirmed that with increasing doping concentration FCA increases; and found that the absorption coefficients obtained from IM can now be used to perform optical simulations of these CSPCs in solar cells., Photovoltaic Materials and Devices, Electrical Sustainable Energy

Published
2020
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36. Performance of diamond detectors for VUV applications

Author

BenMoussa, A., Theissen, A., Scholze, F., Hochedez, J.F., Schühle, U., Schmutz, W., Haenen, K., Stockman, Y., Soltani, A., McMullin, D., Vest, R.E., Kroth, U., Laubis, C., Richter, M., Mortet, V., Gissot, S., Delouille, V., Dominique, M., Koller, S., Halain, J.P, Remes, Z., Petersen, R., D’Olieslaeger, M., and Defise, J.-M.

Published
2006
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42. Improved Contactless Method of IR Reflectance under Grazing Incidence for Measurement of Doping Profiles

Author

Holovsky, J., Remes, Z., Franta, D., Conrad, B., Abelová, L., Bušek, D., and Poruba, A.

Subjects
Silicon Cells, Characterisation & Simulation Methods for Si Cells
Abstract

35th European Photovoltaic Solar Energy Conference and Exhibition; 278-280, We have elaborated contactless method of measurement and evaluation of doping profiles in silicon polished wafers based on infrared reflectance under high angle of incidence. We have found higher angle of incidence increases sensitivity, however approaching Brewster angle increases also experimental error, therefore 65 angle has been chosen. Moreover, to increase reproducibility we divide the measured spectra by reference spectra taken on an undoped sample, and further we rescale the spectra to fixed value in the region of 4000 cm-1–7000 cm-1. To reduce number of evaluated parameter, the carrier profile in boron-doped samples was parametrized by 3 parameters and that in phosphorous-doped samples was parametrized by 4 parameters, using additional empirically determined assumption that the first part of the profile is a constant plateau and that the following two exponential tails are joined at a value of 3x1019 cm-3. As a physical model, the classical Drude equation is used and revised, leading to adjustment of effective mass and assuming concentration-dependent relaxation time and the contribution from band-to-band excitations. The relation of concentration-dependent relaxation time was represented in the range of interest by a power law that significantly deviates from typically used empirical data. The reason is that the empirical data had been obtained as a function of dopant density and not free carrier density. Because the doping efficiency drops at higher concentration this empirical data could not be used. This is one of the most important advancement of the free carrier absorption model. Finally, the model parameters were calibrated independently by infrared ellipsometry. Satisfactory agreement with the profiles measured by the electrochemical capacitance-voltage method was reached. The measurement using Fouriertransform infrared spectrophotometer takes few seconds and can be implemented as an in-line characterization technique in industry.

Published
2018
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45. Large area heavily boron doped nano-crystalline diamond growth by MW-LA-PECVD [Póster]

Author

Taylor, Andy, Ashcheulov, Petr, Zivcova, Zuzana Vlckova, Remzová, M., Kopeček, Jaromír, Hubík, Pavel, Klimša, Ladislav, Remes, Z., Kavan, Ladislav, Beltrán, Ana M., Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte, and Universidad de Sevilla. TEP123: Metalurgia e Ingeniería de los Materiales

Subjects
MW-LA-PECVD, Boron doping, Large area deposition, Conductive diamond
Abstract

Diamond is a unique semiconductor with a wide bandgap which usually is easily doped with boron and is acknowledged as one of the best materials for electrochemical applications. Heavily boron doped, high quality single crystal synthetic diamond can reach electrical conductivity as high as 103 S.cm, whereas polycrystalline material usually reaches c.a. 102 S.cm. However, many potential applications are restricted by the deposition temperature and limited coating area of conventional MW PECVD systems. Deposition of boron doped nano-crystalline diamond (BNCD) layers using a microwave PECVD system with linear antenna delivery (MW-LA-PECVD), enabling large area coating, was first reported in 2014 [1]. However, layers showed lower electrical conductivity in comparison to BNCD layers deposited using conventional PECVD systems. In addition, deposition of BNCD by MW-LA-PECVD is complicated by the necessity for the addition of oxygen species, which are known to limit boron incorporation and the competitive growth of silicon carbide at low CO2 concentrations [2, 3]. In this work, we further study the effect of deposition conditions on the synthesis of BNCD using the MW-LA-PECVD technique. In order to produce highly conductive BNCD with a low sp2 fraction, we have investigated in greater detail the effect of deposition temperature, from 250 °C up to 750 °C, using temperature controlled substrate stages and the effect of precursor gas compositions.

Published
2017

47. Substrate temperature changes during molecular beam epitaxy growth of GaMnAs.

Author

Novák, V., Olejník, K., Cukr, M., Smrcˇka, L., Remesˇ, Z., and Oswald, J.

Subjects
SPECTRUM analysis, MOLECULAR beam epitaxy, ARSENIDES, GALLIUM compounds, MANGANESE compounds
Abstract

Our band gap spectroscopy measurements reveal a remarkably big increase of the substrate temperature during the low-temperature molecular beam epitaxy growth of GaMnAs layers. With the help of numerical simulations we explain the effect as a consequence of changing absorption/emission characteristics of the growing epilayer. We discuss possibilities for reducing the substrate temperature variations during the growth. [ABSTRACT FROM AUTHOR]

Published
2007
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48. Temperature dependence of intrinsic infrared absorption in natural and chemical-vapor deposited diamond.

Author

Piccirillo, Clara, Davies, Gordon, Mainwood, Alison, Scarle, Simon, Penchina, C. M., Mollart, T. P., Lewis, K. L., Nesla´dek, M., Remes, Z., and Pickles, C. S. J.

Subjects
DIAMONDS, CHEMICAL vapor deposition, INFRARED radiation, PHOTONS
Abstract

Empirical rules are derived that describe the temperature dependence of the infrared absorption spectra of pure diamond for photons of energy hv=500-4000 cm[sup -1]. We show that with increasing temperature in the range 14

Published
2002
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49. Large area heavily boron doped nano-crystalline diamond growth by MW-LA-PECVD [Póster]

Author

Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte, Universidad de Sevilla. TEP123: Metalurgia e Ingeniería de los Materiales, Taylor, Andy, Ashcheulov, Petr, Zivcova, Zuzana Vlckova, Remzová, M., Kopeček, Jaromír, Hubík, Pavel, Klimša, Ladislav, Remes, Z., Kavan, Ladislav, Beltrán, A.M., Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte, Universidad de Sevilla. TEP123: Metalurgia e Ingeniería de los Materiales, Taylor, Andy, Ashcheulov, Petr, Zivcova, Zuzana Vlckova, Remzová, M., Kopeček, Jaromír, Hubík, Pavel, Klimša, Ladislav, Remes, Z., Kavan, Ladislav, and Beltrán, A.M.

Abstract

Diamond is a unique semiconductor with a wide bandgap which usually is easily doped with boron and is acknowledged as one of the best materials for electrochemical applications. Heavily boron doped, high quality single crystal synthetic diamond can reach electrical conductivity as high as 103 S.cm, whereas polycrystalline material usually reaches c.a. 102 S.cm. However, many potential applications are restricted by the deposition temperature and limited coating area of conventional MW PECVD systems. Deposition of boron doped nano-crystalline diamond (BNCD) layers using a microwave PECVD system with linear antenna delivery (MW-LA-PECVD), enabling large area coating, was first reported in 2014 [1]. However, layers showed lower electrical conductivity in comparison to BNCD layers deposited using conventional PECVD systems. In addition, deposition of BNCD by MW-LA-PECVD is complicated by the necessity for the addition of oxygen species, which are known to limit boron incorporation and the competitive growth of silicon carbide at low CO2 concentrations [2, 3]. In this work, we further study the effect of deposition conditions on the synthesis of BNCD using the MW-LA-PECVD technique. In order to produce highly conductive BNCD with a low sp2 fraction, we have investigated in greater detail the effect of deposition temperature, from 250 °C up to 750 °C, using temperature controlled substrate stages and the effect of precursor gas compositions.

Published
2017

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