Efficiency enhancement calculations of state-of-the-art solar cells by luminescent layers with spectral shifting, quantum cutting, and quantum tripling function

Solar cells of which the efficiency is not limited by the Shockley-Queisser limit can be obtained by integrating a luminescent spectral conversion layer into the cell structure. We have calculated the maximum efficiency of state-of-the-art c-Si, pc-Si, a-Si, CdTe, GaAs, CIS, CIGS, CGS, GaSb, and Ge solar cells with and without an integrated...

Non-conducting interfaces of LaAlO3/SrTiO3 produced in sputter deposition: The role of stoichiometry

We have investigated the properties of interfaces between LaAlO3 films grown on SrTiO3 substrates singly terminated by TiO2. We used RF sputtering in a high-pressure oxygen atmosphere. The films are smooth, with flat surfaces. Transmission electron microscopy shows sharp and continuous interfaces with some slight intermixing. The elemental ratio...

Origin of an enhanced colossal magnetoresistance effect in epitaxial Nd0.52Sr0.48MnO3 thin films

Nd0.52Sr0.48MnO3 films of various thicknesses have been prepared by dc magnetron sputtering on single crystal LaAlO3 (001) substrates. Reducing the film thickness leads to a significant suppression of ferromagnetic (FM) ordering and the Curie point falls below the antiferromagnetic (AFM) transition temperature. When this occurs, a huge rise of...

Two-dimensional growth, anisotropic polaron transport, and magnetic phase segregation in epitaxial Nd0.52Sr0.48MnO3 films

Nd0.52Sr0.48MnO3 films have been fabricated by dc magnetron sputtering on single-crystal LaAlO3 (001) and SrTiO3 (011) substrates with additional annealing to relax the lattice strain. Although the Nd0.52Sr0.48MnO3 films were deposited simultaneously on different substrates at the same deposition rate, they differ in thickness by a factor of ? ....

Luminescence of Ce3+ at two different sites in ?-Sr2P2O7 under vacuum ultraviolet-UV and x-ray excitation

A series of Ce3+ doped ?-Sr2?2xCexNaxP2O7 phosphor compounds has been prepared using a high-temperature solid-state reaction technique. The luminescence properties under vacuum ultraviolet-UV and x-ray excitation were studied. Luminescence spectra reveal three UV-emitting peaks at about 310, 330, and 350 nm from which we conclude that Ce3+...

Microstructures and the corresponding magnetic properties of half-doped Nd0.5Sr0.5MnO3 films

The microstructural and magnetic properties of amorphous, nanoclustered, and self-organized bilayer Nd0.5Sr0.5MnO3 films, prepared by rf magnetron sputtering, are investigated. The amorphous film was found to be a typical paramagnet with free motion of the individual Mn spins, and the magnetic properties are well described on the basis of the...

Structural modulation and electronic structural features in the charge ordered state of La0.5Sr1.5MnO4

Fabrication of in situ ultrathin anodic aluminum oxide layers for nanostructuring on silicon substrate

The authors demonstrate a method for the fabrication of in situ ultrathin porous anodic aluminum oxide layers (aspect ratio<2:1) on Si, which can be directly used as templates for nanodot preparation and for pattern transfer. The regular shape of the aluminum oxide pores is maintained even when the thickness of the aluminum oxide template is...

Magnetic phase diagram and structural separation of La0.7(Ca1?ySry)0.3MnO3 thin films

The structural, magnetic, and transport properties of La0.7(Ca1?ySry)0.3MnO3 films, deposited on a LaAlO3?(001) single crystalline substrate by rf-magnetron sputtering using “soft” (or powder) targets, have been investigated. It was found that at 0.3 ? y ? 0.5 both the rhombohedral (R3c) and the orthorhombic (Pnma) crystal phases in the form of...

Mechanism of Persistent Luminescence in Eu2+ and Dy3+ Codoped Aluminate and Silicate Compounds

A mechanism of persistent luminescence that was proposed in 1996 for SrAl2O4:Eu2+;Dy3+ has been widely adopted to explain afterglow in many Eu2+ and Dy3+ codoped aluminates and silicates. The mechanism involves the thermally activated release of a hole from Eu2+ in its excited 5d state to the valence band which is subsequently trapped by Dy3+....