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The electronic structure of Vanadium pentoxide (V2O5), a transition metal oxide with an exceedingly large work function of 7.0 eV, is studied via ultraviolet, inverse and x-ray photoemission spectroscopy. Very deep lying electronic states with electron affinity and ionization energy (IE) of 6.7 eV and 9.5 eV, respectively, are found. Contamination due to air exposure changes the electronic structure due to the partial reduction of vanadium to V+4 state. It is shown that V2O5 is a n-type material that can be used for efficient hole-injection into materials with an IE larger than 6 eV, such as 4,4′-Bis(N-carbazolyl)-1,1′-bipheny (CBP). The formation of an interface dipole and band bending is found to lead to a very small energy barrier between the transport levels at the V2O5/CBP interface. [ABSTRACT FROM AUTHOR]

We report on various sexiphenyl derivatives as gain media in organic solid-state lasers. The molecules involved in this research are simple p-sexiphenyl, the laser dye molecule 2,5,2””’,5””’-tetra-t-butyl-p-sexiphenyl (TBS) and the spirolinked sexiphenyl-derivative 2,7-bis(biphenyl-4-yl)-2’,7’-di-tert-butyl-9,9’-spirobifluorene. It appears that the morphology of vacuum-deposited thin films is highly dependent on the sterical dimensions of the respective molecules. Whereas thin films based on simple p-sexiphenyl comprise large clusters which significantly deteriorate their waveguiding properties; films formed by TBS, and the spiroderivative show a dramatically improved morphology with reduced surface roughness. Therefore amplified spontaneous emission (ASE) and lasing are demonstrated in both of the last but not in films based on p-sexiphenyl. Second-order distributed-feedback lasers with TBS as the active medium have been prepared with an emission between 390 and 435 nm depending on the grating period of the Bragg reflector. While the ASE characteristics are similar in films formed by TBS and the spiroderivative, TBS exhibits even superior laser threshold densities which are as low as 45 μJ/cm2 at a wavelength of 396 nm. [ABSTRACT FROM AUTHOR]

An examination is done on the subthreshold characteristics of ballistic carbon nanotube field effect transistors (CNTFETs) revealing the complex band structure effect. In conclusion, it is observed that nanoscale CNTFETs can perform better with a larger on-off current ration and better subthreshold swing if the CNT has a larger band gap.

An examination is done of fabricated fully patterned all-organic thin-film transistors with a variety of organic polymer insulators. In conclusion, a strong correlation is observed between the solvents used for the dielectrics, dielectric constant of the insulator, and the field-effect mobility.

Semitransparent perovskite solar cells (PSCs) are of interest for application in tandem solar cells and building-integrated photovoltaics. Unfortunately, several perovskites decompose when exposed to moisture or elevated temperatures. Concomitantly, metal electrodes can be degraded by the corrosive decomposition products of the perovskite. This is even the more problematic for semitransparent PSCs, in which the semitransparent top electrode is based on ultrathin metal films. Here, we demonstrate outstandingly robust PSCs with semitransparent top electrodes, where an ultrathin Ag layer is sandwiched between SnOx grown by low-temperature atomic layer deposition. The SnOx forms an electrically conductive permeation barrier, which protects both the perovskite and the ultrathin silver electrode against the detrimental impact of moisture. At the same time, the SnOx cladding layer underneath the ultra-thin Ag layer shields the metal against corrosive halide compounds leaking out of the perovskite. Our semitransparent PSCs show an efficiency higher than 11% along with about 70% average transmittance in the near-infrared region (λ > 800 nm) and an average transmittance of 29% for λ = 400-900 nm. The devices reveal an astonishing stability over more than 4500 hours regardless if they are exposed to ambient atmosphere or to elevated temperatures. [ABSTRACT FROM AUTHOR]

The objective of this letter is to show the potential of amorphous indium gallium zinc oxide (IGZO) thin-film transistors (TFT) for designing radio frequency (RF) communication systems operating in the gigahertz regime. For that purpose, the self-mixing operation of in-house fabricated IGZO-TFTs beyond their transit frequency ($f_{T}$) is reported. The bottom-gate, top-contact TFTs have an $f_{T}$ of 40 MHz including the device interconnects. A differential RF self-mixing circuit was fabricated to act as an RF detector and frequency doubler. The detector shows a peak voltage responsivity ($R_{V}$) and a minimum noise equivalent power of 445 V/W and 0.1 nW/ ${\sqrt {\text {Hz}}}$ at 50 MHz and 2 V/W and 30 nW/ ${\sqrt {\text {Hz}}}$ at 1 GHz, respectively, at a chopping frequency of 28 kHz. As a frequency doubler, the circuit can generate a second-harmonic output voltage up to −36 dBV for an 8-dBV RF input voltage at 100 MHz. [ABSTRACT FROM AUTHOR]

European Standards and Guidelines for Quality Assurance in tertiary education at Universities of Applied Sciences recommend a high level of competence orientation. This can be achieved and evaluated by the definition of Learning Outcomes. Furthermore, these Outcomes can assure a comparison of the level of education after graduation. Efforts should be made to achieve this form of Quality Assurance for the professional education of physiotherapists.

Top gated metal-oxide thin-film transistors (TFTs) provide two benefits compared to their conventional bottom-gate counterparts: (i) The gate dielectric may concomitantly serve as encapsulation layer for the TFT channel. (ii) Damage of the dielectric due to high-energetic particles during channel deposition can be avoided. In our work, the top-gate dielectric is prepared by ozone based atomic layer deposition at low temperatures. For ultra-low gas permeation rates, we introduce nano-laminates of Al2O3/ZrO2 as dielectrics. The resulting TFTs show a superior environmental stability even at elevated temperatures. Their outstanding stability vs. bias stress is benchmarked against bottom-gate devices with encapsulation. [ABSTRACT FROM AUTHOR]

This contribution analyzes the reliability of strain and rotation variation determination using cross- as well as phase-only correlation of experimental wide-angle electron backscatter diffraction (EBSD) patterns. For both rotation and three-point bending the resulting displacement gradient tensor components are examined in terms of magnitude and statistical scatter as a function of various correlation procedure parameters and signal-to-noise ratio. It is shown that on the one hand the Fourier filter width has a major impact on the strain results. At higher noise level a smaller filter width has to be applied for obtaining maximum precision. On the other hand, the influence of the degree of overlap of the regions of interest positioned in the patterns is less important. For both rotation and bending experiments the cross-correlation variant yields a smaller standard deviation with respect to phase-only correlation, in particular for elevated noise level. The difference is attributed to the stronger propagation of noise effects in the course of phase-only correlation function calculation and fitting. In the rotation experiment a standard deviation of ∼1.0 × 10−4, averaged over the displacement gradient tensor components, and a rotational precision of ∼1.5 × 10−4 rad have been achieved by using optimized evaluation settings. [ABSTRACT FROM AUTHOR]

Abstract: This article analyzes electron energy-loss near-edge fine structures of the Ruddlesden–Popper system and of the parent compounds and SrO by comparison with first principles calculations. For that, the fine structures of chemical solution deposited Ruddlesden–Popper films have been experimentally recorded by means of transmission electron microscopy. Moreover, density of states computations using an all-electron density-functional code have been performed. It is shown that the appearance and shape of the experimental O–K and fine structure features result from the crystallography-dependent electronic structure of the investigated oxides, which display technologically interesting dielectric as well as lattice–structural properties. [Copyright &y& Elsevier]

Abstract: In this article several experimentally identified Mn valence-sensitive ELNES quantities for the La1−x Sr x MnO3 compound class are presented, namely the energy separations between Mn-L3 and O-Ka, between O-Kb and O-Ka edges, the Mn-L2,3 white line intensity ratio, and the Mn-L3 line width. Valence sensitivities of these quantities are evaluated, and possible additional influences on them are considered. At high signal-to-noise ratio the two energy separations display most sensitively changes of the Mn valency. An experiment-based estimation of the total uncertainties of the quantities indicates that at low signal-to-noise ratio, which is the case when studying interface effects at high spatial resolution, again both energy separations allow to resolve the smallest valency changes. [Copyright &y& Elsevier]

Abstract: This article evaluates the valence sensitivity and accuracy of selected EELS white-line extraction methods based on the white-line intensity ratio in case of manganese oxides, predominantly in the valency range [; ]. For this purpose Mn– ionization edges of several Mn oxides were measured and four different methods were applied to extract the intensities. The obtained ratios have been analyzed in terms of their errors, their scatter, and their sensitivity on manganese valency. We found that the maximum-intensity as well as the Pearson and Walsh–Dray methods show larger relative changes of the ratio between and than curve-fitting. Taking the scatter into account, Walsh–Dray distinguishes more clearly between those two valencies than curve-fitting. Thus the Walsh–Dray method promises the most accurate determination of small valency shifts. [Copyright &y& Elsevier]

In order to achieve laser emission in the visible part of the spectrum, we have investigated the growth of self-assembled InP quantum dots on GaInP by low-pressure metal-organic vapor phase epitaxy (MOVPE) using the Stranski-Krastanow growth mode. Unlike the well-established InAs-GaAs system, when InP is deposited on GaInP, typically, two types of coherently strained islands with different sizes are formed. A high density of small islands is favored when using growth conditions with a reduced surface diffusion, i.e., low temperatures, high growth rates, and substrates with high misorientation angles. After the deposition of 3.4 monolayers of InP at 580°C on GaAs-substrates with a surface angle of 15° to the next (111)B-plane, 2.1010 InP dots per square centimeter with an average height of 4 nm were assembled. The emission of these InP islands at 1.72 eV (4.2 K) shows an inhomogeneous broadening of 42 meV because of the size fluctuation of the quantum dots. At 90 K, lasing from self-assembled InP quantum islands was observed above a threshold current density of 288 A/cm2. The detected laser line is located at 1.8 eV, about 80 meV higher than is the ground-state transition energy. We attribute this behavior to lasing from excited states in agreement with power-dependent photoluminescence experiments. For temperatures above 150 K, the threshold current density increases dramatically because of a thermally activated escape of carriers up to 4.9 k17/cm2 at room temperature, where the characteristic temperature is 35 K. Injection lasers containing stacked InP quantum islands and AlGaInP barrier layers with a higher band offset may exhibit an improved temperature dependence [ABSTRACT FROM PUBLISHER]