M. Godlewski

Warsaw University Of Life Sciences, Warszawa, Masovian Voivodeship, Poland

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Publications (340)527.65 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Thermally evaporated fullerene C60 porous films served as templates for a hybrid (molecular-inorganic) disordered blend formation. C60 films were covered with zinc oxide (ZnO) grown by atomic layer deposition. ZnO filled every pore in the C60 layer which led to the formation of C60–ZnO films with separate and distinguishable phases of C60 and ZnO constituents. Morphological, structural, optical, and electrical properties of the so-obtained films were investigated. Deposition of ZnO polycrystalline films on C60 porous layers resulted in the formation of ZnO with additional structural defects, compared to the films grown on planar substrates, which affected the electrical transport in the ZnO–C60 layers.
    Journal of Materials Science 06/2015; 50(11). DOI:10.1007/s10853-015-8970-8 · 2.31 Impact Factor
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    ABSTRACT: The test structures for photovoltaic (PV) applications based on zinc oxide nanorods (NRs) that were grown using a low-temperature hydrothermal method on p-type silicon substrates (100) covered with Ag nanoparticles (NPs) were studied. The NPs of three different diameters, i.e., 5-10 nm, 20-30 nm, and 50-60 nm, were deposited using a sputtering method. The morphology and crystallinity of the structures were confirmed by scanning electron microscopy and Raman spectroscopy. It was found that the nanorods have a hexagonal wurtzite structure. An analysis of the Raman and photoluminescence spectra permitted the identification of the surface modes at 476 cm−1 and 561 cm−1. The presence of these modes is evidence of nanorods oriented along the wurtzite c-axis. The NRs with Ag NPs were covered with a ZnO:Al (AZO) layer that was grown using the low-temperature atomic layer deposition technique. The AZO layer served as a transparent ohmic contact to the ZnO nanorods. The applicability of the AZO layer for this purpose and the influence of the Ag nanoparticles on the effectiveness of light acquisition by such prepared PV cells were checked by reflectance and transmittance measurements of the AZO/glass and AZO/NPs/glass reference structures. Based on these studies, the high-energy transmittance edge was assigned to the ZnO energy gap, although it is blueshifted with respect to the bulk ZnO energy gap because of Al doping. It was also shown that the most optimal PV performance is obtained from a structure containing Ag nanoparticles with a diameter of 20-30 nm. This result is confirmed by the current-voltage measurements performed with 1-sun illumination. The structures show a plasmonic effect within the short wavelength range: the PV response for the structure with Ag nanoparticles is twice that of the structure without the nanoparticles. However, the influence of the Ag nanoparticle diameters on the plasmonic effect is ambiguous.
    Journal of Applied Physics 05/2015; 117(19):193101. DOI:10.1063/1.4921424 · 2.19 Impact Factor
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    M. Godlewski, A. J. Zakrzewski
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    ABSTRACT: The Symposium F: “Novel materials for electronic, optoelectronic, photovoltaic and energy saving applications” of the 2013 E-MRS Fall Meeting (held in Warsaw, Poland, on 16–20 September 2013) was organized to cover many important aspects of basic and applied research of novel materials for present and future industrial applications. Particular emphasis was given to new technological and application concepts concerning both bulk crystals and various quantum structures of reduced dimensionality, like quantum wells and quantum dots (nanoparticles). The presented results on application-oriented materials were mostly focused on light emitting structures, light detectors, solar cells and materials for spintronics. Special attention was given to the technological aspects and challenges: growth techniques, defect control and structure optimization, doping procedures, optical properties and degradation processes. Relevant experimental techniques and crystal growth procedures were also discussed. Experimental results were compared with theoretical calculations giving deeper insight into many problems of modern materials science. Over 100 researchers from all over the world participated in this symposium, giving in all 15 invited lectures, 38 contributed talks and 70 poster presentations.
    physica status solidi (c) 09/2014; 11(9‐10). DOI:10.1002/pssc.201470060
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    ABSTRACT: Zinc oxide (ZnO) films were used in silicon-based photovoltaic (PV) structures both as an n-type partner to p-type Si and (on top) as a transparent electrode (as a so-called TCO film). Photovoltaic response of such PV structures depends on the electrical properties of n-ZnO films as well as p-Si (100) substrates. The ZnO-based TCO films were deposited by an Atomic Layer Deposition (ALD) method. The films show a high electron concentration (similar to 10(20) cm(-3)) and a relatively high electron mobility ( > 10 cm(2)/V s). Considering Si, we used fairly cheap commercial substrates with 360 mu m thickness, i.e., not optimized for PV cells applications. The best results were obtained for Si substrates with a moderate hole concentration (similar to 10(15) cm(-3)) and resistivity of 10 Omega cm. The photovoltaic efficiency achieved is 4.4%, with the possibility of further improvement.
    Materials Science in Semiconductor Processing 09/2014; 25:190-196. DOI:10.1016/j.mssp.2013.11.026 · 1.76 Impact Factor
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    ABSTRACT: Oxide nanoparticles doped with rare-earth ions are tested for applications as nanomarkers in biology and medicine, e.g. for early cancer diagnostics. In this work we describe properties of such markers obtained by a microwave hydrothermal technology. Nanomarkers based on oxide materials (ZnO) are grown and tested for medical and biological applications.
    Optical Materials 08/2014; 36(10). DOI:10.1016/j.optmat.2013.12.032 · 2.08 Impact Factor
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    ABSTRACT: Aluminum-doped zinc oxide (AZO) films were grown on polyethylene terephthalate (PET) substrates by atomic layer deposition (ALD) at low deposition temperatures (110-140 degrees C). The films have low resistivities, similar to 10(-3) Omega cm, and high transparency (similar to 90%) in the visible range. Bending tests indicated a critical bending radius of approximate to 1.2cm, below which the resistivity changes became irreversible. The films deposited on PET with additional buffer layer are more stable upon bending and temperature changes.
    Materials Science and Engineering B 08/2014; 186. DOI:10.1016/j.mseb.2014.03.002 · 2.12 Impact Factor
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    ABSTRACT: We report on the properties of photovoltaic (PV) structures based on thin films of n-type zinc oxide grown by atomic layer deposition method on a cheap silicon substrate. Thin films of ZnO are used as n-type partner to p-type Si (110) and, when doped with Al, as a transparent electrode. PV structures with different thicknesses of ZnO layers (from 600 nm to 1600 nm) were deposited to determine the optimal performance of PV structures. The best response we obtained for the structure with ZnO layer thickness of 800 nm. The so-obtained PV structures show 6% efficiency.
    Thin Solid Films 07/2014; 563:28–31. DOI:10.1016/j.tsf.2013.10.110 · 1.87 Impact Factor
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    ABSTRACT: Biocompatibility of the new generation of rare-earth-based fluorescent nanocrystals (FNs) has already been confirmed (Godlewski and Godlewski, 2012). Following the intra-gastric gavage (IG), FNs were quickly absorbed by the small intestine epithelium and rapidly (within 24 h) distributed to the majority of the organs and tissues. However, when studying the literature, the huge discrepancies have been found in the distribution patterns of the quantum dots and FNs used by different authors. In this talk the bioavailability of Eu-doped Y2O3 matrix nanocrystals created using the solvothermal method in the Institute of Physics will be compared with their commercially-acquired counterparts. The size and shape of the FNs were examined by the scanning electron microscopy (SEM) and then their persorption from the duodenum was compared after IG in the adult male Balb-c mice. Furthermore, the absorption and distribution patterns of two differently-shaped FNs (Eu:Y2O3 and Pr:ZrO2) were compared. The IF PAN-made and commercially available Y2O3-based FNs differed significantly in shape and size. The in-house FNs were small and columnar-shaped compared to the large and spherical commercial ones. Concomitantly, we found a significantly higher intestinal absorption and distribution to the liver of the IF PAN-made FNs. To check whether the shape or the size of FNs is the determining factor in their bioavailability, we performed the experiment with the much smaller spherical FNs based on ZrO2. We found no differences in the pattern of alimentary uptake or the distribution to the organs between the IF PAN-made Y2O3 and ZrO2 FNs. In the latter part of the talk the transfer of the Y2O3 and ZrO2 FNs through the blood-brain barrier will be discussed.
    XX Ural International Winter School on the Physics of Semiconductors, Ekaterinburg – Novouralsk, Russia; 02/2014
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    ABSTRACT: Aluminum-doped zinc magnesium oxide (Zn1−x Mgx O:Al) films with the Mg content from x = 0 to 0.48 were obtained using atomic layer deposition (ALD). Together with the thorough studies of the properties of the deposited films, the ALD growth parameters conditioning possible applications of Zn1−x Mgx O:Al films as transparent electrodes are investigated. Very low film resistivities (≤~10−3 Ω cm) and the metallic-type conductivity behavior at room temperature for Zn1−x Mgx O:Al films are observed for Mg content x < 0.19. The Mg content of x = 0.19 results in the optical absorption edge of Zn1−x Mgx O:Al films at 3.81 eV (325 nm). Other film parameters like work function or sheet resistance can be easily modified by variation of growth parameters.
    Journal of Materials Science 02/2014; 49(4):1512-1518. DOI:10.1007/s10853-013-7832-5 · 2.31 Impact Factor
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    ABSTRACT: ZnCoO is one of the most studied and promising semiconductor materials for spintronics applications. In this work we discuss optical and electrical properties of ZnCoO films and nanoparticles grown at low temperature by either Atomic Layer Deposition or by a microwave driven hydrothermal method. We report that doping with Cobalt quenches a visible photoluminescence (PL) of ZnO. We could observe a visible PL of ZnO only for samples with very low Co fractions (up to 1%). Mechanisms of PL quenching in ZnCoO are discussed. We also found that ZnO films remained n-type conductive after doping with Co, indicating that a high electron concentration and Cobalt 2+ charge state can coexist.
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    ABSTRACT: A new inexpensive method of the ultra-fast growth of ZnO nanorods from the aqueous solution is described. This environment friendly and fully reproducible method allows growth of nanorods in about 1-3 min time on various substrates, without any catalyst or complexing agent. The substrates need to be coated with a layer of gold droplets, which nucleate the growth. Growth temperature does not exceed 50 degrees C and growth can be performed at atmospheric pressure. Deionised water and zinc acetate are used as oxygen and zinc precursors, respectively. The method is characterised by simplicity and allows regulating size of the ZnO nanorods in a large extent. Due to simplicity and safety of this method, it is suitable for industrial applications, i.e., in the construction of gas sensors or highly sensitive light detectors (changes of sample resistivity upon illumination).
    International Journal of Nanotechnology 01/2014; 11(9/10/11):758. DOI:10.1504/IJNT.2014.063786 · 1.14 Impact Factor
  • Acta Physica Polonica Series a 11/2013; 124(5):869-872. DOI:10.12693/APhysPolA.124.869 · 0.60 Impact Factor
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    ABSTRACT: The paper presents photoemission studies of wide band gap semiconductors surfaces doped with gadolinium and samarium. The contribution of the Gd4f and Sm4f electrons to the electronic structure of the doped semiconductor systems (CdTe, GaN and ZnO) was evaluated based on the Fano resonance measured across the RE4d → RE4f intra-ion photoionization threshold. It was found that the RE valence and position of the RE4f shell varies significantly between the investigated semiconductor systems and depends not only on the used semiconductor matrix but also on the Fermi level position.
    Applied Surface Science 10/2013; 282:326-334. DOI:10.1016/j.apsusc.2013.05.128 · 2.54 Impact Factor
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    ABSTRACT: Optical and magneto-optical properties of ZnCoO films grown at low temperature by Atomic Layer Deposition are discussed. Strong wide band absorption, with onset at about 2.4 eV, is observed in ZnCoO in addition to Co-related intra-shell transitions. This absorption band is related to Co 2+ to 3+ photo-ionization transition. A strong photoluminescence (PL) quenching is observed, which we relate to Co recharging in ZnO lattice. Mechanisms of PL quenching are discussed.
    Optical Materials 08/2013; 34(12). DOI:10.1016/j.optmat.2012.03.031 · 2.08 Impact Factor
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    ABSTRACT: A series of (Zn,Co)O layers with Co contents x up to 40% grown by atomic layer deposition have been investigated. All structures deposited at 160 ∘C show magnetic properties specific to II-VI dilute magnetic semiconductors with localized spins S=3/2 coupled by strong but short-range antiferromagnetic interactions resulting in low-temperature spin-glass freezing for x=0.16 and 0.4. At higher growth temperature (200∘C) metallic Co nanocrystals precipitate in two locations giving rise to two different magnetic responses: (i) a superparamagnetic contribution coming from volume disperse nanocrystals; (ii) a ferromagneticlike behavior brought about by nanocrystals residing at the (Zn,Co)O/substrate interface. It is shown that the dipolar coupling within the interfacial two-dimensional dense dispersion of nanocrystals is responsible for the ferromagneticlike behavior.
    Physical Review B 08/2013; 88(8):085204. DOI:10.1103/PhysRevB.88.085204 · 3.66 Impact Factor
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    ABSTRACT: The results of the Rutherford backscattering/channeling study of ZnO layers are presented. ZnO layers were deposited on the silicon single crystals and GaN epitaxial layers at low temperature by atomic layer deposition. Deposition temperature varied between 100 and 300 degrees C. A random spectra analysis was performed to determine layer thickness and composition. In turn, analysis of the aligned spectra allows us to study evolution of ingrown defects. The Rutherford backscattering study supports the results of X-ray photoelectron spectroscopy measurements, performed separately, that the ZnO-ALD layers deposited at low temperature contain a higher oxygen content. Composition measurements, performed as a function of growth temperature, show that oxygen content decreases with the increasing temperature of the atomic layer deposition growth process.
    Acta Physica Polonica Series a 05/2013; 123(5):899-903. DOI:10.12693/APhysPolA.123.899 · 0.60 Impact Factor
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    ABSTRACT: ZnO films with high conductivity are obtained by atomic layer deposition for the application in solar cells based on CdS/CdTe/Cu2S films. The parameters of solar cells with ZnO electrode are compared with the ones with Mo. The advantages of ZnO electrode are discussed.
    Electronics and Nanotechnology (ELNANO), 2013 IEEE XXXIII International Scientific Conference; 01/2013
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    ABSTRACT: In this paper, we complement our previous work on the study of low-temperature rectifying junctions based on Ag/ZnO Schottky barriers. Diodes characterized by very high ION/IOFF ratio and ideality factors considerably higher than unity, in disagreement with the thermionic emission model, are modeled with a 2-D finite-element simulator. We could discard tunneling and inhomogeneous barrier-height distribution as sources for this anomalous value. A new interface charge layer model was therefore introduced, which is able to reproduce the electrical behavior in devices with large ideality factors without decreasing the rectifying properties.
    IEEE Transactions on Electron Devices 10/2012; 59(10):2762-2766. DOI:10.1109/TED.2012.2207459 · 2.36 Impact Factor
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    ABSTRACT: The paper presents results for zinc oxide films grown at low temperature regime by Atomic Layer Deposition (ALD). We discuss electrical properties of such films and show that low temperature deposition results in oxygen-rich ZnO layers in which free carrier concentration is very low. For optimized ALD process it can reach the level of 10^15 cm-3, while mobility of electrons is between 20 and 50 cm2/Vs. Electrical parameters of ZnO films deposited by ALD at low temperature regime are appropriate for constructing of the ZnO-based p-n and Schottky junctions. We demonstrate that such junctions are characterized by the rectification ratio high enough to fulfill requirements of 3D memories and are deposited at temperature 100degC which makes them appropriate for deposition on organic substrates.
    Semiconductor Science and Technology 07/2012; 27(7-07411):07411. DOI:10.1088/0268-1242/27/7/074011 · 2.21 Impact Factor
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    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 the explanation of contradicted magnetic properties of ZnCoO and ZnMnO reported till now. In this paper, we discuss advantages of the atomic layer deposition (ALD) growth method, which enables us to control the uniformity of ZnMnO and ZnCoO alloys. Properties of ZnO, ZnMnO and ZnCoO films grown by the ALD are discussed.
    Semiconductor Science and Technology 06/2012; 27(7):074009. DOI:10.1088/0268-1242/27/7/074009 · 2.21 Impact Factor

Publication Stats

2k Citations
527.65 Total Impact Points

Institutions

  • 2014
    • Warsaw University Of Life Sciences
      • Department of Physiological Sciences
      Warszawa, Masovian Voivodeship, Poland
  • 2004–2014
    • Cardinal Stefan Wyszynski University in Warsaw
      • Department of Mathematics
      Warszawa, Masovian Voivodeship, Poland
  • 1975–2014
    • Polish Academy of Sciences
      • Institute of Physics
      Warszawa, Masovian Voivodeship, Poland
  • 2000–2012
    • Institute of Physics of the Polish Academy of Sciences
      Warszawa, Masovian Voivodeship, Poland
  • 2011
    • Universitas Kristen Satya Wacana
      Salatiga, Central Java, Indonesia
  • 2009
    • University of Warsaw
      Warszawa, Masovian Voivodeship, Poland
  • 2001
    • Macquarie University
      • Department of Physics and Astronomy
      Sydney, New South Wales, Australia
  • 1981–2000
    • University of Hull
      Kingston upon Hull, England, United Kingdom
  • 1991–1992
    • University of Amsterdam
      • Van der Waals-Zeeman Institute
      Amsterdamo, North Holland, Netherlands
  • 1990
    • Humboldt-Universität zu Berlin
      Berlín, Berlin, Germany
  • 1985–1990
    • Linköping University
      • Department of Physics, Chemistry and Biology (IFM)
      Linköping, Östergötland, Sweden