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105 results on '"Nistor, L.C."'

20. Deposition of high quality TiN films by excimer laser ablation in reactive gas

Author

Mihailescu, I.N., Chitica, N., Nistor, L.C., Popescu, M., Teodorescu, V.S., Ursu, I., Andrei, A., Barborica, A., Luches, A., Giorgi, M. Luisa de, Perrone, A., Dubreuil, B., and Hermann, J.

Subjects
Titanium compounds -- Research, Lasers -- Usage, Gases -- Observations, Physics
Abstract

Highly pure and hard face centered cubic (fcc) TiN films, deposited on cold silicon wafers, promotes Ti target ablation, which occurs under multipulse excimer laser irradiation in a low pressure atmosphere of nitrogen gas. The ablation of Ti targets does not require any thermal treatment. An increase in the surrounding temperature causes a degradation of the crystallinity of the TiN films, although the films are stoichiometric.

Published
1993

24. Incorporation and localization of substitutional <tex>Mn^{2+}$</tex> ions in cubic ZnS quantum dots

Author

Nistor, S.V., Stefan, M., Nistor, L.C., Goovaerts, Etienne, and Van Tendeloo, Gustaaf

Subjects
Condensed Matter::Materials Science, Physics
Abstract

Multifrequency electron paramagnetic resonance (EPR) and high resolution transmission electron microscopy (HRTEM) investigations were performed on small (2 nm) cubic ZnS nanocrystals (quantum dotsQDs) doped with 0.2% mol Mn2+, self-assembled into a mesoporous structure. The EPR data analysis shows that the substitutional Mn2+ ions are localized at Zn2+ sites subjected to a local axial lattice distortion, resulting in the observed zero-field-splitting parameter |D|=41×10−4 cm−1. The local distortion is attributed to the presence in the second shell of ligands of a stacking fault or twin, which alters the normal stacking sequence of the cubic structure. The HRTEM results confirm the presence of such extended planar defects in a large percentage of the investigated QDs, which makes possible the proposed substitutional Mn2+ impurity ions localization model. Based on these results it is suggested that the high doping levels of Mn2+ ions observed in cubic ZnS and possible in other II-VI semiconductor QDs prepared at low temperatures can be explained by the assistance of the extended lattice defects in the impurities incorporation.

Published
2010

25. TEM characterization of ferromagnetic Co-implanted ZnO films

Author

Ghica, C., Nistor, L.C., Kuncser, V.E., Schinteie, G., Epurescu, G., Dinescu, M., Ion, L., Antohe, S., Velisa, G., Ionescu, P., Scintee, N., Pantelica, D., Grob, J.J., Emat G. Van, Tendeloo, and Jung, Marie-Anne

Published
2009

27. A microstructural study of the thermal stability of atomic layer deposited <tex>Al_{2}O_{3}$</tex> thin films

Author

Nistor, L.C., Richard, O., Zhao, O., Bender, H., Stesmans, A., and Van Tendeloo, Gustaaf

Subjects
Physics
Abstract

The thermal stability of amorphous Al2O3 films (similar to8 and 80 nut thick) deposited by atomic layer deposition on HF-last and thin SiO2 covered (001) Si substrates is studied by transmission electron microscopy. The layers are in- and ex-situ annealed in the same temperature range.

Published
2003

42. Synthesis and characterization of Mn2+ doped ZnS nanocrystals self-assembled in a tight mesoporous structure

Author

Nistor, S.V., Nistor, L.C., Stefan, M., Mateescu, C.D., Birjega, R., Solovieva, N., and Nikl, M.

Subjects
*ORGANIC synthesis, *MANGANESE, *LIQUID-liquid equilibrium, *ZINC sulfide, *NANOCRYSTALS, *MOLECULAR self-assembly, *MESOPOROUS materials, *CHEMICAL structure
Abstract

Abstract: We report the synthesis, by a surfactant-assisted liquid–liquid reaction, of nanocrystalline ZnS doped with 0.2 mol% Mn2+ ions self-assembled in a mesoporous structure. The XRD measurements demonstrate the formation of a sponge-like mesoporous material with a tight distribution of pores of 1.8 nm mean diameter built from cubic ZnS nanocrystals of 1.8 nm average size. TEM investigation confirms the formation of the mesoporous structure with walls of 3.1 nm mean thickness built from nanocrystallites of cubic ZnS. The ordering effect of self-assembling, which is reflected in the tight size distribution of crystallites and pores, might be also responsible for the well resolved EPR spectra, attributed to the presence of three types of isolated Mn2+ paramagnetic centers. [Copyright &y& Elsevier]

Published
2009
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44. Influence of the deposition configuration on the composition, structure and morphology of La0.6Y0.07Ca0.33MnO3−δthin films obtained by pulsed laser deposition

Author

Ghica, C, Valeanu, M, Nistor, L.C, Teodorescu, V, Sandu, C, Ristoscu, C, Mihailescu, I.N, Werckmann, J, and Deville, J.-P

Abstract

We present a structural and morphological study on La0.6Y0.07Ca0.33MnO3−δ(LYCMO) thin films deposited by laser ablation onto MgO-buffered silicon wafers using two deposition configurations named on-axisand off-axis. All thin films have been deposited at high temperatures in an oxygen atmosphere. A comparative study between the on-axis and off-axis samples is performed by transmission electron microscopy, electron diffraction and energy dispersive X-ray spectroscopy. The films are polycrystalline and show a columnar morphology. The off-axis sample shows a better crystalline texture, although slight compositional variations have been found.

Published
2001
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