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The integration of both optical and electronic components on a single chip, despite the challenge, holds the promise of compatibility with CMOS technology and high scalability. Among all candidate materials, III-V semiconductor nanostructures are key ingredients for opto-electronics and quantum optics devices, such as light emitters and harvesters. The control over geometry, and dimensionality of the nanostructures, enables one to modify the band structures, and hence provide a powerful tool for tailoring the opto-electronic properties of III-V compounds. One of the most creditable approaches towards such growth control is the combination of using patterned wafer and the self-assembled epitaxy. This work presents monolithically integrated catalyst-free InP nanowires grown selectively on nanotip-patterned (001)Si substrates using gas-source molecular-beam epitaxy. The substrates are fabricated using CMOS nanotechnology. The dimensionality of the InP structures can be switched between two-dimensional nanowires and three-dimensional bulk-like InP islands by thermally modifying the shape of Silicon nanotips, surrounded by the SiO2 layer during the oxide-off process. The structural and optical characterization of nanowires indicate the coexistence of both zincblende and wurtzite InP crystal phases in nanowires. The two different crystal structures were aligned with a type-II heterointerface.

Narrow conduction channels are fabricated from an In0.75Ga0.25As-InP heterostructure using electron-beam lithography and dry etching. The etched surface is realized to be smooth by employing a reactive ion etching. The etching-induced surface conduction is eliminated by removing the damaged surface layer using a diluted HCl solution. The negligible surface depletion for the In-rich quantum well enables to create conducting channels in arbitrary geometries such as in a circular shape. We evidence the presence of a ballistic contribution in the electron transport by demonstrating a rectification of rf excitations that is achieved by the magnetic-field-tuned transmission asymmetry in the circularly-shaped channels. The absence of the surface depletion is shown to cause, on the other hand, a surface scattering for the electrons confined in the channels. An increase of the resistance, including its anomalous enhancement at low temperatures, is induced by the gas molecules attached to the sidewalls of the channels. We also report a large persistent photoconduction, which occurs as a parallel conduction in the undoped InP barrier layer.

Table olives and olive oils are the main dietary sources of hydroxytyrosol (HT), a natural antioxidant compound that has emerged as a potential aid in protection against cardiovascular risk. Bioavailability studies with olive oils showed that HT is bioavailable from its free form and from conjugated forms like oleuropein and its aglycone. Still, its low dietary intake, poor bioavailability, and high inter-individual variability after absorption through the gastrointestinal tract hamper its full benefits.In a randomized, controlled, blind, cross-over study, we investigated the impact of HT metabolism and bioavailability by comparing two olive-derived watery supplements containing different doses of HT (30.58 and 61.48 mg of HT/dosage, respectively); additionally, HT-fortified olive oil was used in the control group. To this aim, plasma and urine samples were evaluated in 12 healthy volunteers following the intake of a single dose of the supplements or fortified olive oil. Blood and urine samples were collected at baseline and at 0.5, 1, 1.5, 2, 4, and 12 hours after intake. HT and its metabolites were analyzed by UHPLC-DAD-MS/MS.Pharmacokinetic results showed that dietary HT administered through the food supplements is bioavailable and biovailability increases with the administered dose. After intake, homovanillic acid, HT-3-O-sulfate, and 3,4-dihydroxyphenylacetic acid are the main metabolites found both in plasma and urine. The maximum concentrations in plasma peaked 30 minutes after intake.Being the bioavailability of a compound a fundamental prerequisite for its effect, these results promise a good potential of both food supplements for the protection against oxidative stress and the consequent cardiovascular risk.

Transparent conducting or semiconducting oxides are important materials for (transparent) optoelectronics and power electronics applications. While most of these oxides can be doped n-type only with room-temperature electron mobilities on the order of 100cm^2/Vs p-type oxides are needed for the realization of pn-junction devices but typically suffer from exessively low (<

The semiconducting oxide $\ensuremath{\beta}$-gallium oxide ($\ensuremath{\beta}\ensuremath{-}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$) possesses a monoclinic unit cell, whose low symmetry generally leads to anisotropic physical properties. For example, its electrical conductivity is generally described by a polar symmetrical tensor of second rank consisting of four independent components. Using van der Pauw measurements in a well-defined square geometry on differently oriented high-quality bulk samples and the comparison to finite-element simulations, we precisely determine the ratio of all elements of the $\ensuremath{\beta}\ensuremath{-}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ three-dimensional electrical conductivity tensor. Despite the strong structural anisotropy, a weakly anisotropic conductivity at and above room temperature was found. In the ${a}^{*}bc$ coordinate system, the diagonal elements deviate from each other by no more than 6%. Based on these results and the off-diagonal element being $\ensuremath{\approx}5%$ of the diagonal ones, the direction of highest conductivity is rotated ${(59\ifmmode\pm\else\textpm\fi{}15)}^{\ensuremath{\circ}}$ from the $c$ direction towards the ${a}^{*}$ direction with a conductivity of $(1.12\ifmmode\pm\else\textpm\fi{}0.09)\ifmmode\times\else\texttimes\fi{}$ that in the perpendicular direction of lowest conductivity. Analysis of the temperature dependence of the anisotropy and mobility of differently doped samples allows us to compare the anisotropy for dominant phonon scattering to that for dominant ionized-impurity scattering. For both scattering mechanisms, the conductivities along the $a$ and $b$ direction agree within 2%. In contrast, the conductivity along the $c$ direction amounts to $0.96\ifmmode\times\else\texttimes\fi{}$ that along the $b$ direction for dominant phonon scattering, and up to $1.12\ifmmode\times\else\texttimes\fi{}$ for ionized-impurity scattering. The transport anisotropies are determined to be larger than the theoretically predicted effective mass anisotropy, suggesting slightly anisotropic scattering mechanisms. We demonstrate that significantly higher anisotropies can be caused by oriented, extended structural defects in the form of low-angle grain boundaries, for which we determined energy barriers of up to 93 meV.

We measure the low-frequency noise in epitaxial β-Ga2O3 grown by MOVPE. Both 1/f and generation-recombination noise components are well resolved. The Hooge parameters characterizing the 1/f noise are 3 × 10–4 at room temperature and 2 × 10–5 at temperatures near 200 K. Mid bandgap trap states result in generation-recombination noise that is analyzed using temperature dependent low-frequency deep-level noise spectroscopy. Trap levels with energies of 165, 127, and 37 meV below the conduction band minimum are characterized in terms of density and activation energy.

We present the growth, fabrication, and characterization of light-emitting diodes based on (Al,Ga)As quantum wells and dots embedded in a p-n GaP structure. Samples were grown on Sulphur-doped GaP (001) substrate using gas-source molecular beam epitaxy. The structures include either GaAs quantum structures with nominal coverage between 1.2 and 3.6 monolayers or Al0.3Ga0.7As quantum wells. For structures with GaAs layer thicker than 1.5 monolayers the 3.6% lattice mismatch in the materials system results in formation of quantum dots via Stranski-Krastanow growth mode with areal density of about 8×1010 cm-2. The atomic-force and transmission-electron microscopy show that with increasing coverage of GaAs from 1.8 to 3.6 monolayers the average lateral size and height of dots change in the range of 17-34 nm and 0.9–2 nm, respectively. The diode structures emit light from the red to the green spectral range up to room temperature. The GaAs/GaP QDs show electroluminescence between 1.8 eV and 2 eV, whereas the Al0.3Ga0.7As quantum wells emit light between 2 eV and 2.2 eV.

(Al,Ga)As/GaP quantum structures show luminescence between 1.7 and 2.2 eV and up to room temperature. Using different growth conditions the morphology of the quantum structures can be changed between well, dot, and dash and the corresponding light emission can be tuned.

The transport properties of n- and p-doped AlP layers grown by gas-source molecular beam epitaxy are investigated. n- and p-types of conductivities are achieved using Si and Be with peak room-temperature mobilities of 59.6 cm2/Vs and 65.0 cm2/Vs for electrons and holes, respectively. Si-doping results are then used for the design of n-doped AlP/GaP distributed Bragg reflectors (DBRs) with an ohmic resistance of about 7.5 ± 0.1 Ω. The DBRs are integrated as bottom mirrors in GaP-based light-emitting diodes (LEDs) containing InGaP/GaP quantum dots. The functionality of the LED structure and the influence of the DBRs on the InGaP/GaP electroluminescence spectra are demonstrated.

In this work we present a comprehensive comparison of ultra thin thermally nitrided (TN) to plasma nitrided (PN) gate dielectrics (GD). We will show that thermal nitridation is a promising technique to increase the nitrogen concentration up to 25%. Furthermore, we will demonstrate that ultra thin thermally nitrided GD have the potential to be an alternative solution compared to plasma nitrided GD. This work includes the analysis of physical and electrical parameters as well as reliability results from reliability characterization. Additionally, we investigated the impact of Deuterium on electrical parameters and reliability behavior.

Thermal behavior and carrier injection of GaAs/GaP quantum-dot light-emitting diodes are investigated. The diodes emit red light between 1.8 eV and 2 eV and operate at room temperature. Adding aluminum to the quantum structures shifts the emission wavelength towards green. Thermal filling and high injection of the carriers in GaAs/GaP quantum dots result in contributions of different radiative recombination channels with higher emission energies and hence a blueshift of the electroluminescence with increasing temperature and very small thermal quenching of the light output.