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Article Dans Une Revue Thin Solid Films Année : 2007

Composition, structural and electrical properties of thin films prepared by laser ablation of neodymium-doped potassium gadolinium tungstate

Résumé

Thin films were grown on (001) SiO2, SiO2/(100) Si or (100) MgO substrates by laser ablation of neodymium-doped potassium gadolinium tungstate (Nd:KGW) single crystal target. The films were deposited at temperatures between room temperature and 750 degrees C and pressures between 1 X 10(-4) Pa and 50 Pa of oxygen ambient. The influence of the deposition conditions on the composition, structure, morphology and electrical properties of the films was investigated. Special attention was paid to the films deposited in vacuum (I X 10(-4) Pa) or at very low oxygen pressures. Under such conditions, the potassium (K), gadolinium (Gd) and oxygen (0) content decreased strongly as the temperature was increased. At room temperature, the films were K and 0 stoichiometric, in contrast with Gd, which showed a concentration twice higher. The films were polycrystalline, with the exception of those deposited at temperatures below 500 degrees C, which were amorphous. However, all were smooth and dense. The films grown in vacuum and at temperatures between 500 and 700 degrees C consist mainly of ``a-tungsten'' - tungsten oxide (W3O) phase. The films grown on SiO2/Si possessed the best surface quality with nano-size relief The resistivity measurements as a function of the temperature showed that the films produced in vacuum and at temperatures below 500 degrees C were highly insulating, whereas at 600 degrees C they exhibited semiconducting behavior or a metallic one at 700 degrees C. This behavior can be attributed to the existence of various valence states for tungsten below W6+ in the films and to their crystal structure. (c) 2006 Elsevier B.V. All rights reserved.

Dates et versions

hal-01281491 , version 1 (02-03-2016)

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Citer

P. A. Atanasov, A. Og. Dikovska, J. Perriere, R. M. Defourneau. Composition, structural and electrical properties of thin films prepared by laser ablation of neodymium-doped potassium gadolinium tungstate. Thin Solid Films, 2007, 515 (5), pp.3052-3056. ⟨10.1016/j.tsf.2006.08.018⟩. ⟨hal-01281491⟩
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