We report on the fabrication of superconducting MgB 2 thin films on textured Cu(100) tape under low pressure and temperature by using a hybrid physical-chemical vapor deposition (HPCVD) technique to explore the possible broad range of deposition. Thermodynamic calculations for the Mg-B system have been carried out and the pressure-temperature phase diagram was obtained. Our results demonstrate that the deposition of superconducting MgB 2 films is possible beyond the theoretically calculated growth window, where the sublimation of Mg is taking place. The structural and microstructural investigations reveal that MgB 2 films are c-axis-oriented normal to the substrate. The highest J c of ∼1.34 × 10 5 A cm −2 at 5 K under 3 T is obtained for the film grown at 460 • C. The critical current density (J c ) and flux pinning force density (F p ) of MgB 2 films are enhanced with decreasing growth temperature. This could be attributed to the high density of grain boundaries which may act as effective flux pinning centers. These findings suggest an alternative route to fabricate MgB 2 tapes at low temperature for large scale applications.

Nanostructured silicon was formed by means of the ionized N 2 gas reaction on SiO 2 /Si, and the electronic structure, surface morphology, and optical properties were investigated. The physicochemically modified thin layers were resolved to SiN y and SiO x N y through the observation of Si 2p, O 1s, and N 1s core-level spectra in x-ray photoelectron spectroscopy. The formations of SiO x N y and SiO 2 nanostructures ͑3-4 nm in size͒, performed by the etching process followed by adsorption of ionized nitrogen, were confirmed by atomic force microscopy. The nanocrystalline Si ͑6 nm in size͒ distributed within the modified layer ͑approximately 10 nm thick͒ was observed after the in situ rapid thermal annealing processes, using high-resolution transmission electron microscopy. Photoluminescence with a wavelength peaking at around 400 nm was emitted from the nanocrystalline Si formed from the SiO x N y /SiO 2 /Si structures. This work suggests that the nanocrystalline-Si formation and the nanostructured surface modification method, using the controlled ionized gas, were simple and efficient methods requiring low energy and low temperatures.