Wiley

ZnO thin films were fabricated using PLD, sputtering, e‐beam evaporation and sol‐gel techniques. The films were annealed in an oxygen environment to improve their crystallinity. Photoluminescence efficiency and angular emission patterns were characterized and are reported in absolute radiometric units. Conversion efficiencies in the range of 1 – 7 · 10^‐6 were found for the PLD films, 7 · 10^‐6 for a sputtered film, 7 – 40 · 10^‐6 for the e‐beam evaporated films, and 20 – 400 · 10^‐6 for the Sol‐Gel films. In most cases, the angular emission pattern of the photoluminescence was lambertian in nature. Non‐lambertian emission patterns were observed for some films with microstructure, achieved with PLD and e‐beam evaporation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

We report details about the quantitative analysis of B and P impurities in the concentration range between 1 × 10¹⁴ and 1 × 10¹⁷ cm^–3 by photoluminescence (PL) in solar‐grade Si (SOG‐Si). The intensity ratio of impurity‐bound exciton (BE) to free exciton (FE) at 4.2 K was used as a measure of the impurity concentration in the range between 5 × 10¹⁰ and 1 × 10¹⁵ cm^–3 in the standard PL method. We raised the sample temperature to enhance the FE emission, which enabled us to extend the concentration range higher. The sample temperature was accurately determined from the FE‐line shape. We deduced a formula for the determination of the B and P concentrations in the higher range from the BE/FE ratio and the sample temperature (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

In this paper, we investigate gallium co‐doping during CZ crystallization of boron and phosphorus compensated Si. It is shown that the addition of gallium yields a fully p‐type ingot with high resistivity despite high B and P contents in the silicon. Segregation of doping impurities is consistent with theory. Minority carrier lifetime and majority carrier mobility measurements indicate that this material is suitable for the realization of solar cells with comparable efficiencies to standard material. Significant light‐induced degradation of minority carrier lifetime is however revealed to occur in this material. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

GaN films with thickness up to 3 mm were grown by halide vapour phase epitaxy method. Two growth modes were observed: the high temperature (HT) mode and the low temperature (LT) mode. Films grown in HT mode had smooth surface, however the growth stress was high and caused cracking. Films grown in LT mode had rough surface with high density of V‐defects (pits), however, such films were crack‐free. The influence of growth parameters on the pit shape and evolution was investigated. Origins of pits formation and process of pit overgrowth are discussed. Crack‐free films with smooth surface and reduced density of pits were grown using combination of the LT and HT growth modes. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

We investigated the electronic structure of BaFeO₃ by using HAXPES and XAS measurements and first principle studies. The experimental and theoretical results indicated that BaFeO₃ is a negative charge transfer compound. We concluded that the on‐site Coulomb energy and the strong hybridization between Fe‐3d and O‐2p orbitals play a very important role of emergence of negative charge transfer. And we found the new structure in the Fe‐2p XPS spectrum and concluded this structure is originated from non‐local screening. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

This paper describes improvements of the tribological properties and the biocompatibility of Ti₆Al4V alloy implanted by oxygen plasma immersion (PIII) in comparison with other treatments like thermal oxidation, conventional beamline ion implantation (II) of nitrogen and a combination of both thermal oxidation and II of nitrogen.

Ball‐on‐disc friction and wear tests were performed to investigate the modifications introduced for each treatment. Biocompatibility tests were carried out by controlling Al and V ion migration in a Hank's solution simulating the human body fluid. The reported results indicate that PIII provide a promising method to improve the characteristics of the Ti₆Al₄V alloy to be used in human body implants. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The irradiation of carbon based nanostructures with ions and electrons has been shown to be an appropriate tool to tailor their properties. The defects induced in the nanostructures during irradiation are able to modify their mechanical and electronic properties. Here we simulate the irradiation of carbon nanotubes with carbon ions using a molecular dynamics code. We use the Tersoff potential joined smoothly to the Universal Ziegler‐Biersack‐Littmark potential at short distances. We study the number of defects produced after irradiation with a single carbon ion finding a saturation with its energy at ∼ 3 keV. We observe, after continuum irradiation with low energy ions, the formation of bumps in the irradiated region. For larger energy ions we find that the diameter of the nanotube shrinks as shown in previous works. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The photoluminescence and its temperature dependence have been investigated for the ensembles of InAs quantum dots embedded in symmetric In_0.15Ga_0.85As/GaAs quantum wells with different PL intensities. The solution of the set of rate equations for exciton dynamics was used to analyze the nature of thermal activation energies of the QD photoluminescence quenching. It is revealed two different stages of thermally activated quenching of the QD PL intensity caused by thermal escape of excitons from the In_0.15Ga_0.85As/GaAs QW into the GaAs barrier and from the QDs into the QWs with their subsequent nonradiative recombination. The variety of activation energies of PL thermal quenching is discussed as well. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Transparent conducting undoped and indium‐doped zinc oxide (ZnO) thin films have been deposited by the spray pyrolysis method at 350 °C substrate temperature. X‐ray diffraction spectra of the films have shown that the films are polycrystalline and hexagonal wurtzite in structure. The average optical transmittance of 1% indium‐doped ZnO thin films was over 84% in the visible range. The direct band gap value of the undoped ZnO film was calculated. Electrical conductivity measurement of Ag‐ZnO:In‐Ag structures have been carried out using the two‐probe method in dark, in the range of temperature from 90 to 320 K. The conductivity of undoped and indium‐doped ZnO films increases with increase in temperature. The incorporation of indium in the ZnO film enhanced the conductivity. The conductivity of 1 at.% In‐doped film is higher than undoped ZnO at room temperature. The activation energies E_a values in the range of 90‐320 K temperatures were also determined. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)