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189 results on '"Kopalko, K"'

2. ZnO, ZnMnO and ZnCoO films grown by atomic layer deposition

Author

Łukasiewicz, M. I., Wójcik-Głodowska, A., Guziewicz, E., Wolska, A., Klepka, M. T., Dłużewski, P., Jakieła, R., Łusakowska, E., Kopalko, K., Paszkowicz, W., Wachnicki, Ł., Witkowski, B. S., Lisowski, W., Krawczyk, M., Sobczak, J. W., Jabłoński, A., and Godlewski, M.

Subjects
Condensed Matter - Materials Science
Abstract

Despite many efforts the origin of a ferromagnetic (FM) response in ZnMnO and ZnCoO is still not clear. Magnetic investigations of our samples, not discussed here, show that the room temperature FM response is observed only in alloys with a non-uniform Mn or Co distribution. Thus, the control of their distribution is crucial for explanation of contradicted magnetic properties of ZnCoO and ZnMnO reported till now. In the present review we discuss advantages of the Atomic Layer Deposition (ALD) growth method, which enables us to control uniformity of ZnMnO and ZnCoO alloys. Properties of ZnO, ZnMnO and ZnCoO films grown by the ALD are discussed., Comment: 41 pages, 19 figures, 48 references, review paper

Published
2013
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3. Puzzling magneto-optical properties of ZnMnO films

Author

Godlewski, M., Wasiakowski, A., Ivanov, V. Yu., Wojcik-Glodowska, A., Lukasiewicz, M., Guziewicz, E., Jakiela, R., Kopalko, K., and Zakrzewski, A.

Subjects
Condensed Matter - Materials Science
Abstract

Optical and magneto-optical properties of ZnMnO films grown at low temperature by Atomic Layer Deposition are discussed. A strong polarization of excitonic photoluminescence is reported, surprisingly observed without splitting or spectral shift of excitonic transitions. Present results suggest possibility of Mn recharging in ZnO lattice. Strong absorption, with onset at about 2.1 eV, is related to Mn 2+ to 3+ photo-ionization. We propose that the observed strong circular polarization of excitonic emission is of a similar character as the one observed by us for ZnSe:Cr., Comment: 19 pages, 4 figures, 38 references

Published
2011
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4. MnAs dots grown on GaN(0001)-(1x1) surface

Author

Kowalik, I. A., Kowalski, B. J., Iwanowski, R. J., Kopalko, K., Łusakowska, E., and Sawicki, M.

Subjects
Condensed Matter - Materials Science
Abstract

MnAs has been grown by means of MBE on the GaN(0001)-(1x1) surface. Two options of initiating the crystal growth were applied: (a) a regular MBE procedure (manganese and arsenic were delivered simultaneously) and (b) subsequent deposition of manganese and arsenic layers. It was shown that spontaneous formation of MnAs dots with the surface density of 1$\cdot 10^{11}$ cm$^{-2}$ and $2.5\cdot 10^{11}$ cm$^{-2}$, respectively (as observed by AFM), occurred for the layer thickness higher than 5 ML. Electronic structure of the MnAs/GaN systems was studied by resonant photoemission spectroscopy. That led to determination of the Mn 3d - related contribution to the total density of states (DOS) distribution of MnAs. It has been proven that the electronic structures of the MnAs dots grown by the two procedures differ markedly. One corresponds to metallic, ferromagnetic NiAs-type MnAs, the other is similar to that reported for half-metallic zinc-blende MnAs. Both system behave superparamagnetically (as revealed by magnetization measurements), but with both the blocking temperatures and the intra-dot Curie temperatures substantially different. The intra-dot Curie temperature is about 260 K for the former system while markedly higher than room temperature for the latter one. Relations between growth process, electronic structure and other properties of the studied systems are discussed. Possible mechanisms of half-metallic MnAs formation on GaN are considered., Comment: 20+ pages, 8 figures

Published
2007
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10. Role of intrinsic and extrinsic defects in H implanted hydrothermally grown ZnO.

Author

Schifano, R., Jakiela, R., Galeckas, A., Kopalko, K., Herklotz, F., Johansen, K. M. H., and Vines, L.

Subjects
SECONDARY ion mass spectrometry, LITHIUM ions, ZINC oxide, CARRIER density
Abstract

The impact of hydrogen in ZnO is revealed by combining reaction dynamics calculations with temperature dependent Hall (TDH), photoluminescence, and secondary ion mass spectrometry measurements performed on H, 2 H, and He implanted ZnO. H and 2 H box profiles with a concentration ranging from ∼ 3 × 10 17 cm − 3 to ∼ 10 19 cm − 3 and He to produce as much as damage as in the [H] ∼ 3 × 10 17 cm − 3 case were implanted in the samples. The formation of Li lean regions has been observed for [ 2 H] < 10 19 cm − 3 after annealing at 400 ° C. This is attributed to Li i presence consequent to the diffusion of Zn i created during the H/ 2 H implantation process. Results extracted from the TDH measurements performed prior to the annealing at 400 ° C evidence that Li i contributes to an increase in carrier concentration up to ∼ 10 17 cm − 3 by providing a donor level with an activation energy of ∼ 40 meV and thus is very close to the value of ∼ 47 meV expected for H in the oxygen site. The reaction dynamics analysis evidences that the amount of Li i introduced is decreasing at higher H implantation doses as a result of increasing V Zn and H-V Zn retrapping, reactions in which Li i is competing with H. Overall, due to Li i formation as well as the presence of Al the maximum percentage of the implanted H or 2 H acting as a donor in the investigated range is found to be ≲ 2%, which is considerably lower than previously reported. [ABSTRACT FROM AUTHOR]

Published
2019
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18. Correlations between the structural transformations and concentration quenching effect for RE-implanted ZnO systems

Author

Ratajczak, R., Mieszczynski, C., Prucnal, S., Krajewski, T. A., Guziewicz, E., Wozniak, W., Kopalko, K., Heller, R., Akhmadaliev, S., Ratajczak, R., Mieszczynski, C., Prucnal, S., Krajewski, T. A., Guziewicz, E., Wozniak, W., Kopalko, K., Heller, R., and Akhmadaliev, S.

Abstract

In this paper, we present optical, structural and electrical studies of the phenomenon called concentration quenching effect occurring in ZnO doped with Rare Earth (RE) ions. For this purpose, the epitaxial ZnO layers grown by the Atomic Layer Deposition (ALD) are doped by ion implantation with Yb and Er elements with fluencies ranging from 5 × 1013 to 1 × 1016/cm2. In order to activate optically the implanted RE and to remove defects, the post-implantation thermal annealing was performed at 800 °C for 10 min in the O2 atmosphere using a Rapid Thermal Annealing (RTA) system. Two-step processed samples, before and after annealing, were evaluated by Rutherford Backscattering Spectrometry (RBS/c) to investigate the damage build-up process in the ZnO lattice after RE ion bombardment and the lattice site location of RE. The annealed samples were examined using the photoluminescence (PL) spectroscopy and Hall effect measurements. Our studies show that the luminescence quenching effect, as well as the electrical resistivity response to the increased RE concentration, are strongly connected with the threshold of the structural transformation due to defects accumulation. It suggests that during structural transformations the RE-ion centers are sufficiently close together to be able to interact and transfer the excitation energy between each other, increasing ipso facto the probability to lose the excitation energy by non-radiative processes. Moreover, in contrast to the popular belief, that the concentration quenching effect in RE-doped ZnO depends strongly on the kind of RE-doped ion, the presented results do not provide any evidence to support such an assumption.

Published
2020

23. ZnO grown by atomic layer deposition: A material for transparent electronics and organic heterojunctions.

Author

Guziewicz, E., Godlewski, M., Krajewski, T., Wachnicki, Ł., Szczepanik, A., Kopalko, K., Wójcik-Głodowska, A., Przezdziecka, E., Paszkowicz, W., Łusakowska, E., Kruszewski, P., Huby, N., Tallarida, G., and Ferrari, S.

Subjects
ZINC oxide thin films, TRANSPARENT electronics, HETEROJUNCTIONS, HEAT budget (Geophysics), PHOTOLUMINESCENCE
Abstract

We report on zinc oxide thin films grown by atomic layer deposition at a low temperature, which is compatible with a low thermal budget required for some novel electronic devices. By selecting appropriate precursors and process parameters, we were able to obtain films with controllable electrical parameters, from heavily n-type to the resistive ones. Optimization of the growth process together with the low temperature deposition led to ZnO thin films, in which no defect-related photoluminescence bands are observed. Such films show anticorrelation between mobility and free-electron concentration, which indicates that low n electron concentration is a result of lower number of defects rather than the self-compensation effect. [ABSTRACT FROM AUTHOR]

Published
2009
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24. Extremely low temperature growth of ZnO by atomic layer deposition.

Author

Guziewicz, E., Kowalik, I. A., Godlewski, M., Kopalko, K., Osinniy, V., Wójcik, A., Yatsunenko, S., Łusakowska, E., Paszkowicz, W., and Guziewicz, M.

Subjects
ZINC oxide thin films, ZINC compounds, SOLID state electronics, SURFACES (Technology), LOW temperatures
Abstract

We report on the zinc oxide (ZnO) thin films obtained by the atomic layer deposition (ALD) method using diethyl zinc and water precursors, which allowed us to lower deposition temperature to below 200 °C. The so-obtained “as grown” ZnO layers are polycrystalline and show excitonic photoluminescence (PL) at room temperature, even if the deposition temperature was lowered down to 100 °C. Defect-related PL bands are of low intensity and are absent for layers grown at 140-200 °C. This is evidence that extremely low temperature growth by ALD can result in high quality ZnO thin films with inefficient nonradiative decay channels and with thermodynamically blocked self-compensation processes. [ABSTRACT FROM AUTHOR]

Published
2008
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25. RBS/c and PL studies of ZnO implanted with Pr ions

Author

Ratajczak, R., Prucnal, S., Mieszczynski, C., Guziewicz, E., Stachowicz, M., Snigurenko, D., Kopalko, K., Witkowski, B. S., Krajewski, T. A., and Turos, A.

Subjects
Rare Earths, ZnO, flash lamp annealing, ion implantation, photoluminescence
Abstract

High-quality ZnO epitaxial layers deposited by Atomic Layer Deposition were implanted at room temperature with 150 keV Pr3+ions to fluence of 1x1015 and 2x1015. Two different types of annealing on as implanted samples were performed: rapid thermal annealing (RTA) and flash lamp annealing (FLA). Crystalline quality, damage recovery and Yb lattice site location were evaluated by the Channeling Rutherford Backscattering Spectrometry (RBS/c). The optical properties were studied by photoluminescence (PL). Upon annealing defects recovery has been observed. After RTA the return of Zn atoms to their substitutional sites produces displacement RE atoms into interstitial positions. The increase of RTA temperature and time leads to enhanced out-diffusion of RE atoms. Consequently, better recovery of the crystal structure is accompanied by lower photoluminescence (PL) efficiency. The FLA precludes the RE-atom surface segregation. The substitutional fraction of Pr ions is higher than after RTA with the same structure recovery, but PL intensity from Pr3+ is lower. This suggests that the substitutional RE atoms are preferentially in the 2+ state. Acknowledgments: The work was supported by the NCBiR (Poland) project PBS2/A5/34/2013 and by the EU 7th FP project REGPOT-CT-2013-316014 (EAgLE), by the Polish Ministry of Science and Higher Education (3418/SPIRIT/2015/0) and by the Helmholtz Zentrum Dresden-Rossendorf (HZDR) in a frame of the program Access to Infrastructure (15100222-ST and 16000696-ST).

Published
2016

26. Deep traps in the ZnO nanorods/Si solar cells

Author

Gwozdz, K., primary, Placzek-Popko, E., additional, Zielony, E., additional, Paradowska, K.M., additional, Pietruszka, R., additional, Witkowski, B.S., additional, Kopalko, K., additional, Godlewski, M., additional, and Chang, Liann-be, additional

Published
2017
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30. ZnO as a conductive layer prepared by ALD for solar cells based on n-CdS/n-CdTe/p-Cu₁.₈S heterostructure

Author

Semikina, T.V., Mamykin, S.V., Godlewski, M., Luka, G., Pietruszka, R., Kopalko, K., Krajewski, T.A., Gierałtowska, S., Wachnicki, L., and Shmyryeva, L.N.

Abstract

ZnO films with high conductivity are obtained by atomic layer deposition for application in solar cells based on n CdS/ n CdTe / p Cu₁.₈S heterostructure. The parameters of solar cells with ZnO electrode are calculated from light and dark currentvoltage characteristics and compared with those obtained for structures with Mo contact. The advantages of ZnO electrode are discussed.

Published
2013

32. Atomic layer deposition of thin films of ZnSe - Structural and optical characterization

Author

Guziewicz, E, Godlewski, M, Kopalko, K, Łusakowska, E, Dynowska, E, Guziewicz, M, Godlewski, MM, and Phillips, M

Subjects
Applied Physics
Abstract

Thin films of sphalerite-type ZnSe were grown by atomic layer deposition (ALD) from elemental Zn and Se precursors. These films, grown on various substrates, show bright blue 'edge' emission accompanied by donor-acceptor pair emissions in the blue, green and red spectral regions. Red, green and blue emissions mixed together give a white color, with a color temperature between 2400 and 4500 K depending on a layer thickness and temperature. ZnSe grown by ALD is in consequence a promising material for the fabrication of semiconductor-based white light emitting thin film electroluminescence displays. © 2003 Elsevier B.V. All rights reserved.

Published
2004

36. ZnO as a conductive layer for solar cells based on II-VI materials

Author

Semikina, T. V., primary, Mamykin, S. V., additional, Shmyryeva, L. N., additional, Lashkarev, V., additional, Godlewski, M., additional, Luka, G., additional, Pietruszka, R., additional, Kopalko, K., additional, Krajewski, T. A., additional, Gieratowska, S., additional, and Wachnicki, L., additional

Published
2013
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37. Characteristics of ZnO : As/GaN heterojunction diodes obtained by PA-MBE

Author

Przezdziecka, E, primary, Wierzbicka, A, additional, Reszka, A, additional, Goscinski, K, additional, Droba, A, additional, Jakiela, R, additional, Dobosz, D, additional, Krajewski, T A, additional, Kopalko, K, additional, Sajkowski, J M, additional, Stachowicz, M, additional, Pietrzyk, M A, additional, and Kozanecki, A, additional

Published
2012
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38. Structure Dependent Conductivity of Ultrathin ZnO Films

Author

Snigurenko, D., primary, Kopalko, K., additional, Krajewski, T.A., additional, Łuka, G., additional, Gierałtowska, S., additional, Witkowski, B.S., additional, Godlewski, M., additional, Dybko, K., additional, Paszkowicz, W., additional, and Guziewicz, E., additional

Published
2012
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39. Thin films of ZnO and ZnMnO by atomic layer epitaxy

Author

Wojcik, A, Kopalko, K, Godlewski, M, Lusakowska, E, Guziewicz, E, Minikayev, R, Paszkowicz, W, Swiatek, K, Klepka, M, Jakiela, R, Kiecana, M, Sawicki, M, Dybko, K, Phillips, MR, Wojcik, A, Kopalko, K, Godlewski, M, Lusakowska, E, Guziewicz, E, Minikayev, R, Paszkowicz, W, Swiatek, K, Klepka, M, Jakiela, R, Kiecana, M, Sawicki, M, Dybko, K, and Phillips, MR

Published
2005

40. ZnO, ZnMnO and ZnCoO films grown by atomic layer deposition

Author

Łukasiewicz, M I, primary, Wójcik-Głodowska, A, additional, Guziewicz, E, additional, Wolska, A, additional, Klepka, M T, additional, Dłużewski, P, additional, Jakieła, R, additional, Łusakowska, E, additional, Kopalko, K, additional, Paszkowicz, W, additional, Wachnicki, Ł, additional, Witkowski, B S, additional, Lisowski, W, additional, Krawczyk, M, additional, Sobczak, J W, additional, Jabłoński, A, additional, and Godlewski, M, additional

Published
2012
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42. Monocrystalline thin films of ZnSe and ZnO grown by atomic layer epitaxy

Author

Kopalko, K, Godlewski, M, Guziewicz, E, Łusakowska, E, Paszkowicz, W, Domagała, J, Dynowska, E, Szczerbakow, A, Wójcik, A, Phillips, MR, Kopalko, K, Godlewski, M, Guziewicz, E, Łusakowska, E, Paszkowicz, W, Domagała, J, Dynowska, E, Szczerbakow, A, Wójcik, A, and Phillips, MR

Abstract

We report on the growth of monocrystalline thin films of ZnSe and ZnO by atomic layer epitaxy by simple reaction between elemental precursors. Structural and optical properties of these films are discussed with reference to the investigations performed with atomic force microscopy, scanning electron microscopy, cathodoluminescence and photoluminescence. © 2004 Elsevier Ltd. All rights reserved.

Published
2004

43. Monocrystalline ZnO films grown by atomic layer epitaxy - growth and characterization

Author

Munoz, M, Tamargo, M, Furdyna, J, Luo, H, Kopalko, K, Godlewski, M, Lusakowska, E, Paszkowicz, W, Domagala, JZ, Szczerbakow, A, Ivanov, VY, Godlewski, MM, Phillips, MR, Munoz, M, Tamargo, M, Furdyna, J, Luo, H, Kopalko, K, Godlewski, M, Lusakowska, E, Paszkowicz, W, Domagala, JZ, Szczerbakow, A, Ivanov, VY, Godlewski, MM, and Phillips, MR

Published
2004

44. Epitaxial ZnO Films Grown at Low Temperature for Novel Electronic Application

Author

Wachnicki, Ł., primary, Dużyńska, A., additional, Domagala, J.Z., additional, Witkowski, B.S., additional, Krajewski, T.A., additional, Przeździecka, E., additional, Guziewicz, M., additional, Wierzbicka, A., additional, Kopalko, K., additional, Figge, S., additional, Hommel, D., additional, Godlewski, M., additional, and Guziewicz, E., additional

Published
2011
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50. Origin of white color light emission in ALE-grown ZnSe

Author

Godlewski, M, Guziewicz, E, Kopalko, K, Łusakowska, E, Dynowska, E, Godlewski, MM, Goldys, EM, Phillips, MR, Godlewski, M, Guziewicz, E, Kopalko, K, Łusakowska, E, Dynowska, E, Godlewski, MM, Goldys, EM, and Phillips, MR

Abstract

We discuss light emission properties from thin films of ZnSe grown by atomic layer epitaxy on GaAs (100). White color emission is observed in photoluminescence and cathodoluminescence, due to the observation of three RGB emission bands. We demonstrate possibility of color tuning by either variation of film thickness or, in cathodoluminescence experiments, variation of an accelerating voltage. © 2002 Elsevier Science B.V. All rights reserved.

Published
2003

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