Ion-Beam-Induced Atomic Mixing in Ge, Si, and SiGe, Studied by Means of Isotope Multilayer Structures.

Crystalline and preamorphized isotope multilayers are utilized to investigate the dependence of ion beam mixing in silicon (Si), germanium (Ge), and silicon germanium (SiGe) on the atomic structure of the sample, temperature, ion flux, and electrical doping by the implanted ions. The magnitude of mixing is determined by secondary ion mass spectrometry. Rutherford backscattering spectrometry in channeling geometry, Raman spectroscopy, and transmission electron microscopy provide information about the structural state after ion irradiation.

Combining light-harvesting with detachability in high-efficiency thin-film silicon solar cells.

Efforts to realize thin-film solar cells on unconventional substrates face several obstacles in achieving good energy-conversion efficiency and integrating light-management into the solar cell design. In this report a technique to circumvent these obstacles is presented: transferability and an efficient light-harvesting scheme are combined for thin-film silicon solar cells by the incorporation of a NaCl layer. Amorphous silicon solar cells in p-i-n configuration are fabricated on reusable glass substrates coated with an interlayer of NaCl.

Novel back-reflector architecture with nanoparticle based buried light-scattering microstructures for improved solar cell performance.

A new back-reflector architecture for light-management in thin-film solar cells is proposed that includes a morphologically smooth top surface with light-scattering microstructures buried within. The microstructures are pyramid shaped, fabricated on a planar reflector using TiO2 nanoparticles and subsequently covered with a layer of Si nanoparticles to obtain a flattened top surface, thus enabling growth of good quality thin-film solar cells. The optical properties of this back-reflector show high broadband haze parameter and wide angular distribution of diffuse light-scattering.

Aluminum nanoparticles for plasmon-improved coupling of light into silicon.

This paper investigates the improved photo-current response obtained by depositing Al nanoparticles on top of a Si diode. Well defined Al nanodiscs with a diameter and height of 100 nm are produced on the surface of a Si diode using electron-beam lithography, and the change in photo-current generation is characterized. A blue shift of the photo-current response is demonstrated, substantially improving the relation between gains and losses compared to what is typically observed in similar schemes using Ag nanoparticles.

Auger-decay dynamics of germanium nano-islands in silicon.

The decay dynamics of self-assembled germanium islands is studied by time-resolved fluorescence spectroscopy. The scaling behavior of the decay rate with the number of excitons in the islands is shown to agree with expectations for an Auger-recombination-dominated process in the asymptotic limit of high exciton numbers. The multi-excitonic decay time and spectral behavior are compared to theoretical estimates.

Quasiparticle electronic and optical properties of the Si-Sn system.

The Si(1-x)Sn(x) material system is an interesting candidate for an optically active material compatible with Si. Based on density functional theory with quasiparticle corrections we calculate the electronic band structure of zinc-blende SiSn under both compressive and tensile strain. At 2.

Fibronectin adsorption, cell adhesion, and proliferation on nanostructured tantalum surfaces.

The interaction between dental pulp derived mesenchymal stem cells (DP-MSCs) and three different tantalum nanotopographies with and without a fibronectin coating is examined: sputter-coated tantalum surfaces with low surface roughness <0.2 nm, hut-nanostructured surfaces with a height of 2.9 +/- 0.

Ab initio calculation of electronic and optical properties of metallic tin.

The electronic and optical properties of the metallic bcc and β-Sn phases of tin are studied using density functional theory. The effects of spin-orbit coupling are examined and significant splittings are found in the band structures for both phases. Based on ab initio band structures we calculate the anisotropic optical response of β-Sn.