Application of modulated optical reflectance method for high-temperature superconducting film characterization

Pencheva, V.; Penchev, S.; Naboko, V.; Naboko, S.; Donchev, T.

doi:10.1016/j.vacuum.2004.07.062

Cited by 4 publications

(1 citation statement)

References 5 publications

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“…The potential of MOR for device quality assessment of high-temperature superconducting (HTS) thin-film devices was also demonstrated [8,9]. It was used in particular for room-temperature non destructive evaluation of the surface homogeneity of YBCO thin films for microwave applications [8,10].…”

Section: Introductionmentioning

confidence: 99%

Modulated optical reflectance measurements on La2∕3Sr1∕3MnO3 thin films

Méchin

Flament

Perry

et al. 2005

Journal of Applied Physics

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The modulated optical reflectance (MOR) measurement technique was applied to colossal magnetoresistive materials, in particular, La 2/3 Sr 1/3 MnO 3 (LSMO) thin films. The contactless measurement scheme is prospective for many applications spanning from materials characterization to new devices like reading heads for magnetically recorded media.A contrasted room temperature surface scan of a 100 µm wide 400 µm long bridge patterned into LSMO film provided preliminary information about the film homogeneity. Then the temperature was varied between 240 and 400 K, i.e. through the ferromagnetic to paramagnetic transition. A clear relation between the MOR signal measured as function of the temperature and the relative derivative of the resistivity up to the Curie temperature was observed. This relationship is fundamental for the MOR technique and its mechanism was explored in the particular case of LSMO. Analysis in the framework of the Drude model showed that, within certain conditions, the measured MOR signal changes are correlated to changes in the charge carrier concentration.2

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Section: Introductionmentioning

confidence: 99%

Modulated optical reflectance measurements on La2∕3Sr1∕3MnO3 thin films

Méchin

Flament

Perry

et al. 2005

Journal of Applied Physics

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Laser Heterodyne Measurement of Photothermal Displacement for Material Surface Characterization

Pencheva

Penchev

Naboko

et al. 2006

Plasma Processes & Polymers

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Summary: Double‐heterodyne photodisplacement technique (PDT), based on the detection of the thermal expansion of a sample under irradiation by laser light has been employed to improve the resolution of photothermal displacement measurements up to orders of sub‐picometers. We have developed an ultra‐sensitive system to measure photothermal displacement of metallic and non‐metallic materials, such as silicon, due to the illumination by an ordinary laser diode. Non‐destructive characteristics of the scheme are well suited for conditions that restrict access to the sample to be measured. Careful consideration is given to eliminate the noise sources, so as to achieve the level of sensitivity that needed to detect the structural inhomogeneity of materials. Good agreement between experimental results and theoretical predictions is demonstrated.Laser double‐heterodyne detection of the photo‐thermal expansion of metallic and non‐metallic materials illuminated by a laser diode.imageLaser double‐heterodyne detection of the photo‐thermal expansion of metallic and non‐metallic materials illuminated by a laser diode.

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