Bruit en 1/f de films minces de manganite La0,7Sr0,3MnO3 pour application en bolométrie

Abstract : The large temperature coefficient of resistance in manganite thin films around room temperature makes this material very promising for uncooled microbolometer applications. The measurement of the low frequency noise is needed before practical applications. My thesis was particularly devoted to the study of the temperature coefficient of resistance and the 1/f noise in La0,7Sr0,3MnO3 (LSMO) thin films. LSMO thin films on two different substrates (SrTiO3 et (LaAlO3)0,3(Sr2AlTaO6)0,7) have been grown by pulsed laser deposition. The samples with different geometries were prepared by photolithography and ion etching. The samples connected by four probes were measured using a low noise amplifier showing a Johnson noise level 1,3 nV∙Hz-1/2 and cut-off frequency at 10 Hz. Study by X-Ray diffraction, and the measurements of magnetization, of magnetoresistance and of R(T) which indicate the general quality of the films have been carried out. We mainly attempted to verify the semi-empiric Hooge relation (as a function of the frequency, of the bias current and of the different geometries). The noise measurements in the temperature range from 300 to 400 K have revealed a noise behavior at phase transition without any excess noise. Hooge parameters of about 1 – 3 have been measured, which is among the best reported values in literature. We have finally made an estimation from the results of noise measurements and R(T) measurements.
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  • HAL Id : tel-00130063, version 1

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Fan Yang. Bruit en 1/f de films minces de manganite La0,7Sr0,3MnO3 pour application en bolométrie. Micro et nanotechnologies/Microélectronique. Université de Caen, 2005. Français. ⟨tel-00130063⟩

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