D. Grambole

Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Saxony, Germany

Are you D. Grambole?

Claim your profile

Publications (119)157.1 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Nominally undoped, hydrothermally grown ZnO single crystals have been investigated before and after exposure to remote H-plasma. Defect characterization has been made by two complementary techniques of positron annihilation: positron lifetime spectroscopy and coincidence Doppler broadening. The high-momentum parts of the annihilation photon momentum distribution have been calculated from first principles in order to assist in defect identification. The positron annihilation results are supplemented by Atomic Force Microscopy for characterization of the crystal surface. It was found that virgin ZnO crystal contains Zn-vacancies associated with hydrogen. H-plasma treatment causes a significant reduction in concentration of these complexes. Physical mechanism of this effect is discussed in the paper.
    Defect and Diffusion Forum 09/2012; 331:113. DOI:10.4028/www.scientific.net/DDF.331.113 · 0.31 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Characterization of point defects in a fully stabilized ZrO2 + 9 mol.% Y2O3 single crystal with cubic structure was performed in this work. It was found that the crystal contains a high density of vacancy-like defects characterized by a lifetime of 175 ps. First principle theoretical calculations showed that this lifetime is comparable with lifetime of positrons trapped in zirconium vacancies associated with hydrogen. In particular, in the vicinity of the zirconium vacancy hydrogen forms an O-H bond with one of the nearest neighbour oxygen atoms. The calculated bond length is close to 1 Å. Using nuclear reaction analysis it was found that the hydrogen concentration in the crystal is 0.3 at.%. This amount of hydrogen is sufficient to form zirconium vacancy - hydrogen complexes capable of saturated positron trapping.
    Journal of Physics Conference Series 12/2011; 262(1). DOI:10.1088/1742-6596/262/1/012038
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Surface changes in ZnO single crystals electrochemically doped with hydrogen were investigated in this work using slow positron implantation spectroscopy (SPIS) combined with atomic force microscopy (AFM) and optical microscopy. It was found that hexagonally shaped pyramids were formed on the surface of hydrogen-loaded crystals. The formation of these pyramids can be explained by hydrogen-induced plastic deformation realized by a slip in the [0001] direction. Such a picture is supported (i) by AFM where steps of a height comparable with the c-lattice parameter were found at the base of the pyramids, and (ii) by SPIS which revealed a defected subsurface layer, formed by the hydrogen-induced plastic deformation and exhibiting an enhanced concentration of open-volume defects in hydrogen-loaded crystals.
    Journal of Physics Conference Series 12/2011; 262(1). DOI:10.1088/1742-6596/262/1/012050
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hydrogen release from various elastomers upon irradiation with H+, He+ and Ar+ ions has been studied using nuclear reaction analysis (NRA) method. A massive loss of hydrogen atoms upon irradiation has been noted, the results point to the saturation of hydrogen content at about 10 at.%. The analysis of the experimental data indicates that the hydrogen release is controlled by inelastic collisions between ions and target electrons.
    Materials Chemistry and Physics 05/2011; 127(s 1–2):342–346. DOI:10.1016/j.matchemphys.2011.02.015 · 2.13 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Arsenic doped ZnO and ZnMgO films were deposited on SiO{sub 2} using radio frequency magnetron sputtering and ZnO-Zn{sub 3}As{sub 2} and ZnO-Zn{sub 3}As{sub 2}-MgO targets, respectively. It was found that thermal activation is required to activate the formation of p-type conductivity. Hall measurements showed that p-type films with a hole concentration of {approx}10{sup 17} cm{sup -3} and mobility of {approx}8 cm{sup 2} V{sup -1} s{sup -1} were obtained at substrate temperatures of 400-500 deg. C The shallow acceptor formation mechanism was investigated using x-ray photoelectron spectroscopy, positron annihilation, low temperature photoluminescence, and nuclear reaction analysis. The authors suggest that the thermal annealing activates the formation of the As{sub Zn}-2V{sub Zn} shallow acceptor complex and removes the compensating hydrogen center.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 05/2011; 29(3):03A103. DOI:10.1116/1.3525639 · 2.14 Impact Factor
  • Source
    Material Research Society Spring Meeting; 01/2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A distributed electron cyclotron resonance (DECR) plasma reactor powered by a microwave generator operating at 2.45 GHz (800 W) was used to deposit (t)a-C:H thin films at RT on <100> Si substrates RF biased within the range 25<\V(o)\<600 V. C(2)H(2) was used as precursor. The plasma pressure was varied within the range 0.1 <P<l.5 mtorr. The films were analyzed using spectroscopic ellipsometry (SE) and Fourier transform infrared (FTIR) spectroscopy. The hydrogen content N(H) and the density of the films were determined from nuclear reaction analysis (NRA) using the resonance at 6.385 MeV of the reaction: (15)N + (1)H-->(12)C + (4)He + omega. Position annihilation spectroscopy was used to detect the porosity. The evolutions of N(H) as a function of the substrate ion current density n+ and as a function of V(o) show that the hydrogen incorporation results from the competition between chemisorption and deposited energy density related effects. The increase of the hydrogen incorporation leads to a decrease in the film density and a lower deposition rate. The porosity of the films deposited at low pressure (^O. 1 mTorr) with V(o)= -80 V has been detected. The comparison between results of SRIM-2000 simulations and the evolution of N(H) as a function of V(o) shows that the porosity and the hydrogen content are not correlated. The absorption of oxygen and nitrogen for the low density films has been detected from the observation of the 3250-4000 cm(-1) infrared (IR) band.
    MRS Online Proceeding Library 01/2011; DOI:10.1557/PROC-675-W10.3.1
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ion-beam induced hydrogen migration has been studied in triple layer structures, a-Si/a-Si:H/a-Si and SiO2/a-Si:H/SiO2. Nuclear reaction analysis has been used for simultaneous irradiation with MeV ions and measurement of hydrogen distribution in the structures. It has been established that there is no hydrogen loss from SiO2/a-Si:H/SiO2 structures, but an asymmetric redistribution due to hydrogen penetration into the bottom SiO2 layer. Hydrogen loss has been observed from the a-Si/a-Si:H/a-Si structures. The inspection of the surface of these samples by means of atomic force microscope has shown that it proceeds by bubble formation and blistering at the inner interface. The observed ion-beam induced selective penetration of hydrogen into the underlying material can be used as a tool for preparation of microcavity and microchannel arrays.
    Journal of Physics Conference Series 12/2010; 253(1):012055. DOI:10.1088/1742-6596/253/1/012055
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Nominally undoped, hydrothermally grown ZnO single crystals have been investigated before and after exposure to remote H plasma. Structural characterizations have been made by various positron annihilation spectroscopies (continuous and pulsed slow positron beams, conventional lifetime). The content of bound hydrogen (H-b) before and after the remote H plasma treatment at the polished side of the crystals was determined at depths of 100 and 600 nm, respectively, using nuclear reaction analysis. At a depth of 100 nm, H-b increased from (11.8 ± 2.5) to (48.7 ± 7.6) × 1019 cm−3 after remote H plasma treatment, whereas at 600 nm no change in H-b was observed.
    Physica Status Solidi (A) Applications and Materials 11/2010; 207(11):2415 - 2425. DOI:10.1002/pssa.200925609 · 1.62 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Arsenic-doped ZnMgO films were fabricated on SiO2 by the radio frequency magnetron sputtering technique at different substrate temperatures during growth. The yielded films were characterized by room temperature Hall measurement, x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, secondary ion mass spectroscopy, nuclear reaction analysis and low-temperature photoluminescence. As-doped samples grown at low substrate temperature (350 °C) were n-type conducting (n ~ 1018 cm−3), with evidence showing that the hydrogen impurity was an important shallow donor associated with the observed n-type conduction. Conversion of n-type to p-type conduction being observed at the substrate temperature of ~400 °C was associated with the formation of the AsZn(VZn)2 shallow acceptor complex and the drastic reduction of the hydrogen content.
    Semiconductor Science and Technology 07/2010; 25(8):085009. DOI:10.1088/0268-1242/25/8/085009 · 2.21 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We applied proton microbeam particle-induced X-ray emission (µ-PIXE) for mapping Ca, Zr, Ba and Yb, and atomic force microscopy (AFM) for imaging the surface landscape of a dental composite which releases Ca2+ and F− for the protection of hard dental tissues. Three areas ∼250 × 250 µm2 located ∼0.5–2 mm apart on a smooth surface specimen were mapped with 3.1 MeV protons focused to a ∼3.0 µm spot and at ∼3.9 µm pixel size sampling. The maps evidenced particles with diameters of 3.2–32 µm (Ca), 20–60 µm (Zr), ≤ 4 µm (Ba) and 10–50 µm (Yb). Cross-section area histograms of Ca-rich particles fitted with 2–6 Poisson functions revealed a polydisperse size distribution and substantial differences from an area to another, possibly implying large local variations of Ca2+ released in the hard tissue near a dental filling of a few millimeters in diameter. Such imbalances may lead to low local Ca2+ protection of the dental tissue, favoring the onset of secondary caries. Similarly, AFM images showed high zone-dependent differences in the distributions of grains with apparent diameters of 1–4 µm, plausibly recognized as Ca- and Ba-containing particles. In a simple model based on demineralization data, lateral diffusion of Ca2+ between adjacent domains containing high- and low-area Ca-rich grains is described by exponential concentration gradients. These gradients may generate appreciable electromotive forces, which may enhance electrochemically the local tissue demineralization. Similar effects are to be expected in the protective action of F− ions released from microgranules of YbF3 and of Ba fluoroaluminosilicate glass. Copyright © 2010 John Wiley & Sons, Ltd.
    X-Ray Spectrometry 05/2010; 39(3):208 - 215. DOI:10.1002/xrs.1251 · 1.19 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The plasma-enhanced chemical vapour deposition (PECVD) of amorphous hydrogenated carbon films from pulsed discharges with frequencies in the range from 50kHz to 250kHz was investigated. Five different hydrocarbons (acetylene C2H2, isobutene C4H8, cyclopentene C5H8, toluene C7H8 and cycloheptatriene C7H8) were probed as film growth precursors. In addition, two types of pulse-generators with somewhat different waveforms were used to power the discharges in the so called mid-frequency range. The a-C:H films deposited in a parallel-plate reactor were characterised for their thickness/deposition rate, hardness and hydrogen content. The hydrogen concentration in the films varied between 19at.-% and 37at.-%. With the substrate temperature held constant, it is roughly in inverse proportion to the hardness. The film with the highest hardness of 25GPa was formed at a deposition rate of 0.8μm/h in the C2H2 discharge at the lowest investigated pressure of 2Pa. With increasing molecular mass of the precursor mostly weaker films were deposited. Relatively high values of both deposition rate and hardness were achieved using the precursor isobutene: a hardness of 21GPa combined with a deposition rate of 4.1μm/h. From the probed precursors, isobutene is also most advantageous for a-C:H deposition at higher pressures (up to 50Pa investigated). But, as an over-all trend, the a-C:H hardness decreases with increasing deposition rate.
    Vacuum 03/2010; 85(4):510-513. DOI:10.1016/j.vacuum.2010.10.006 · 1.43 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Abstract— The enrichment of fluorine on the surface of Antarctic meteorites is investigated by applying the nuclear reactions 19F(p, αγ)16O or 19F(p, p'γ)19F with the proton induced gamma emission (PIGE) technique, a class of nuclear reaction analysis (NRA). Results for the Antarctic meteorites ALHA77294, TIL 82409, LEW 86015, ALHA77003, and ALH 83108 are presented. Possible sources of terrestrial F are: volcanic exhalation, tephra layers (volcanic glass), continental soil dust, or sea spray. Material from blue-ice dust-band samples also shows concentrations of F that are significantly higher than the bulk concentrations of meteorites. Finally, a quick investigation for Antarctic meteorites by external PIGE is proposed, leading to a F-contamination index that supplements the qualitative ABC-weathering index.
    01/2010; 38(5):759 - 765. DOI:10.1111/j.1945-5100.2003.tb00040.x
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A comparative study of hardness of thin films of hydrogenated amorphous silicon (a-Si:H) and hydrogen-free amorphous silicon (a-Si) was carried out to reveal the role of hydrogen in the plastic properties of amorphous silicon. In addition, the effect of hydrogen on hardness was established by changing hydrogen concentration in the material using post-deposition processing of the samples. The hydrogen concentration in a-Si:H was decreased by thermal annealing. In a-Si hydrogen was introduced by plasma hydrogenation. The values of hardness of the as-prepared a-Si and a-Si:H films were determined by nanoindentation using depth profiling. Low-depth indentation was applied to evaluate the effect of post-hydrogenation. The results obtained show that the presence of hydrogen in the amorphous silicon network leads to the increase in hardness. The conducted experiments demonstrate that plasma hydrogenation can be used as an effective tool to increase the hardness of amorphous silicon. Hardness of a-Si:H of about 12.3–12.7GPa is as high as of crystalline silicon, suggesting a-Si:H can be a substitute for crystalline silicon in some MEMS.
    Applied Physics A 01/2010; 102(1):131-135. DOI:10.1007/s00339-010-6026-0 · 1.69 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The anomalous wear-out phenomena of Eu-implanted metal-oxide-semiconductor devices were investigated. It will be shown that in contrast to other rare earth elements the electroluminescence (EL) intensity of Eu-implanted SiO <sub>2</sub> layers can rise under constant current injection before the known EL quenching will start. Under certain circumstances, this rise may amount up to two orders of magnitude. The EL behavior will be correlated with the microstructural and electrical properties of the devices. Transmission electron microscopy and Rutherford backscattering spectroscopy were applied to trace the development of Eu/Eu oxide clusters and the diffusion of Eu to the interfaces of the gate oxide layer. The hydrogen profile within the SiO <sub>2</sub>– SiON interface region was determined by nuclear reaction analysis. Current-voltage characteristics, EL decay times, and the progression of the voltage and the EL spectrum with increasing charge injection were measured to study charge and trapping phenomena in the oxide layer to reveal details of the EL excitation mechanism. A first qualitative model for the anomalous life time behavior is proposed.
    Journal of Applied Physics 01/2010; 106(12-106):123103 - 123103-10. DOI:10.1063/1.3272781 · 2.19 Impact Factor
  • Spectrochimica Acta Part B Atomic Spectroscopy 11/2009; 64:1198-1203. DOI:10.1016/j.sab.2009.08.007 · 3.15 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: ZnO nanostructures are of special interest for device applications. However, their structural characterization remains an ongoing challenge. This paper reviews recent efforts and latest achievements in this direction. Results comprise PAS in the form of Slow Positron Implantation Spectroscopy (SPIS) and Pulsed Low Energy Positron Lifetime Spectroscopy (PLEPS), Nuclear Reaction Analysis (NRA), Atomic Force Microscopy (AFM), conductive AFM (C-AFM), Nuclear Magnetic Resonance (NMR), Electron Spin Resonance (ESR), Photoluminescence (PL) spectroscopy, and latest theoretical investigations of structure-related and positron properties of selected defects. The fundamental importance of a relationship between fabrication conditions, native defect formation, and resulting optical and electronic properties is demonstrated by getting either inferior (nanorods) or significantly improved (tetrapods) optical properties compared to single crystal samples, depending on the nanostructure fabrication method. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
    physica status solidi (c) 10/2009; 6(11):2556 - 2560. DOI:10.1002/pssc.200982081
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study is focused on tailoring the porosity of Nb2O5 films during reactive pulsed magnetron sputtering. Dense amorphous films containing nanopores only in deeper regions have been grown at a high rate using substrate temperatures below 60 °C. The films exhibit a high refractive index, n400=2.54, a low extinction coefficient, k400~6×10-4, a low mechanical stress (-90 MPa), and a negligible thermal shift. The specific depth distribution of the nanopores is believed to be the reason for the optimum trade-off between a high refractive index and low mechanical stress.
    Applied Physics Letters 08/2009; 95(8):1904-081904. DOI:10.1063/1.3212731 · 3.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Electron paramagnetic resonance (EPR) spectroscopy of hydrogen-doped indium oxide (IO) tubular nanostructures shows presence of paramagnetic oxygen vacancies (VO) at room temperature. For temperatures below 80 K, the EPR spectra exhibit two distinct split resonances correspond to S=12 hydrogen electron spin. Interestingly, presence of hydrogen EPR resonances is accompanied by absence of EPR signal of VO, which is restored above 80 K with the concomitant disappearance of signature resonances from hydrogen. The temperature dependent donor and passivation behavior of hydrogen has been directly observed in metal oxide. This could provide valuable explanations of various VO induced controversial properties of IO nanostructures.
    Applied Physics Letters 07/2009; 95(1-1). DOI:10.1063/1.3159786 · 3.52 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Micro-PIXE investigations on some Transylvanian chondritic meteorite fragments and on small Moon soil pieces from the LUNA-16 mission were performed at the Legnaro and Rossendorf proton microprobes. The most exciting finding of the study was the presence of Pt grains in the Moci meteorite. The results are compared to previously published data.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 06/2009; 267(13-14):2233-2235. DOI:10.1016/j.nimb.2009.03.017 · 1.12 Impact Factor

Publication Stats

1k Citations
157.10 Total Impact Points

Institutions

  • 1992–2012
    • Helmholtz-Zentrum Dresden-Rossendorf
      • • Institute of Radiation Physics
      • • Institute of Ion Beam Physics and Materials Research
      Dresden, Saxony, Germany
  • 2008
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
  • 2007
    • Bulgarian Academy of Sciences
      Ulpia Serdica, Sofia-Capital, Bulgaria
  • 2004
    • University of Cambridge
      Cambridge, England, United Kingdom
  • 1998
    • Hungarian Academy of Sciences
      • MTA Institute of Nuclear Research
      Budapest, Budapest fovaros, Hungary
    • University of Leipzig
      • Institute for Medical Physics and Biophysics
      Leipzig, Saxony, Germany
  • 1996
    • Universitätsmedizin Göttingen
      Göttingen, Lower Saxony, Germany