The influences of both high-voltage stress and hygrothermal stress were studied for homojunction and heterojunction crystalline Si photovoltaic (PV) modules. In order to separately access the influence of these stresses, these PV modules were subjected to sequential tests with hygrothermal stress and high-voltage stress for various stress durations of each test. It was found that for p-type homojunction crystalline Si PV modules hygrothermal stress applied in advance considerably enhances potential-induced degradation (PID) by high-voltage stress. High-voltage stress applied in advance also accelerates finger-electrode degradation by hygrothermal stress. It was also clarified that hygrothermal stress for short duration applied in advance considerably enhances PID by high-voltage stress for n-type heterojunction crystalline Si PV modules. The possible mechanisms for these accelerated degradation phenomena by the combined stresses are presented.

The effect of annealing on a MgO substrate was systematically investigated, varying the annealing temperature, for preparation of high-quality YBa2Cu3O x (YBCO) films by pulsed laser ablation. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were carried out for characterization of the MgO substrate, and X-ray diffraction (XRD) measurement, including θ-2θ scan, ω-scan (rocking curve) and φ-scan, and electrical measurement were carried out for characterization of YBCO films. Thermal annealing of MgO above 1000° C in oxygen ambient was found to give rise to a great improvement of the crystallinity and the reproducibility of crystal orientation of YBCO films, while it was also found to induce Ca segregation on the surface of MgO and reduce the oxygen content of YBCO films. Annealing below 1000° C causes no outstanding improvement in the crystal structure of YBCO. On the MgO substrate annealed at 1200° C c-axis-oriented YBCO film was found to reproducibly show a full width at half-maximum (FWHM) of the rocking curve of 0.3°, an FWHM of (005) diffraction of 0.1°, an epitaxial relation without in-plane misorientation, a critical zero temperature of 89 K, and a critical current density of 106 A/cm2 at 77.4 K and zero field.

Pb(Zr0.52Ti0.48)O3 films were prepared on an r-plane sapphire substrate by laser ablation using the ArF excimer laser. This is the first report on the preparation of Pb(Zr0.52Ti0.48)O3 films by laser ablation. The composition of the deposited films was found to be fairly close to the composition of the target material for a wide range of the substrate temperature, 400–750°C. The substrate temperature greatly influences the crystal structure; a low substrate temperature produces a pyrochlore phase and a high substrate temperature (750°C) a perovskite phase.

Silicon nitride (SiN x ) films on Si and poly(ethylene terephthalate) (PET) substrates were prepared at approximately 150 C by catalytic chemical vapor deposition (Cat-CVD), using a SiH 4 /NH 3 gas mixture. A water vapor transmission rate as low as 0.2 g/m 2 day and an O 2 gas transmission rate of 0.6 cm 3 /m 2 day were achieved for a stoichiometric Si 3 N 4 film of 77 nm thickness. Although these transmission rates depended on N/Si ratio, no optical absorption was observed under preferable deposition conditions.

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