Low-frequency flux noise in current-carrying high critical temperature superconducting films A highly sensitive ac susceptometer has been fabricated using a commercially available thin film Hall sensor of effective area 25ϫ25 m 2 . This instrument allows measurements of superfluid density and dynamical behavior of vortices in thin film superconductors over a broad range of frequency ͑10 Hz-100 kHz͒, temperature ͑4.2-300 K͒, and ac-field amplitude ͑2-150 Oe͒, and in static magnetic field as high as 5 T collinear with the ac field. The applicability of the susceptometer has been tested on Y 1 Ba 2 Cu 3 O 7 films of thickness as small as ϳ7 nm.

Measurements of the critical current density (Jc) and irreversibility field [Birr(T)] of epitaxial, c-axis-oriented EuBa2Cu3O7 (Eu-123) films are reported. The transition temperature (Tc), Jc, and Birr(T) of these pulsed-laser-deposited films depend critically on the growth temperature (TD), growth rate (Gr), and the oxygen partial pressure (pO2) during growth. As compared to YBa2Cu3O7, Eu-based films require lower Gr, higher pO2, and higher TD. These differences are attributed to the lower adatom mobility of Eu and its propensity for a 2+ oxidation state. The lattice mismatch between (100) LaAlO3 and the ab-plane of Eu-123 leads to an elongated c axis and some randomly oriented islands whose growth is truncated by epitaxial lateral overgrowth as the film thickness increases.

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Understanding the dynamics of vortex matter subjected to random and correlated pinning disorders in layered superconductors remains a topic of considerable interest. The dynamical behavior of vortices in these systems shows a rich variety of effects due to many competing interactions. Here, we study the ac response of as-grown as well as heavy-ion-irradiated Tl 2 Ba 2 CaCu 2 O 8 (Tl-2212) thin films by using a micro Hall-probe susceptometer. We find that the dynamics of vortices in the high-temperature, low-field regime of the H -T phase diagram investigated here depends on the nature of pinning defects. While the decay of screening currents J (t) indicates a glassy behavior in both types of samples, the nature of the glassy phase is different in the two cases. Samples with columnar defects show distinct signature of a Bose glass in the measurement of J (t) and the angular dependence of the irreversibility field (B irr ).

The simplified hybrid (SH) process is the platform on which EPV Solar will develop a cost effective CIGS module manufacturing process.We have already implemented the SH process in our large area deposition system. In this report optimization of the Na access to the absorber layer was done by controlling the Cr underlayer thickness. In addition, CIGS process parameters have been modified to get a more uniform layer attaining good efficiency throughout the substrate at lower temperature. This helped us to make mini module using our existing equipment design. Post-CIGS treatments of samples to passivate the surface before CdS chemical bath deposition have improved our earlier samples. However, this has been found to be less beneficial for newly processed samples reducing the overall processing steps. A textured ZnO window layer deposited on the buffer layer increased device J sc by 5% by reducing reflectance of incident light.