Philips

About: Philips is a company organization based out in Vantaa, Finland. It is known for research contribution in the topics: Signal & Layer (electronics). The organization has 68260 authors who have published 99663 publications receiving 1882329 citations. The organization is also known as: Koninklijke Philips Electronics N.V. & Royal Philips Electronics.

A “Melanopic” Spectral Efficiency Function Predicts the Sensitivity of Melanopsin Photoreceptors to Polychromatic Lights

Abstract: Photoreception in the mammalian retina is not restricted to rods and cones but extends to a small number of intrinsically photosensitive retinal ganglion cells expressing the photopigment melanopsi...

Epitaxial growth of InP nanowires on germanium.

Abstract: The growth of III-V semiconductors on silicon would allow the integration of their superior (opto-)electronic properties with silicon technology. But fundamental issues such as lattice and thermal expansion mismatch and the formation of antiphase domains have prevented the epitaxial integration of III-V with group IV semiconductors. Here we demonstrate the principle of epitaxial growth of III-V nanowires on a group IV substrate. We have grown InP nanowires on germanium substrates by a vapour-liquid-solid method. Although the crystal lattice mismatch is large (3.7%), the as-grown wires are monocrystalline and virtually free of dislocations. X-ray diffraction unambiguously demonstrates the heteroepitaxial growth of the nanowires. In addition, we show that a low-resistance electrical contact can be obtained between the wires and the substrate.

Metal Oxide Induced Charge Transfer Doping and Band Alignment of Graphene Electrodes for Efficient Organic Light Emitting Diodes

Abstract: The interface structure of graphene with thermally evaporated metal oxide layers, in particular molybdenum trioxide (MoO3), is studied combining photoemission spectroscopy, sheet resistance measurements and organic light emitting diode (OLED) characterization. Thin (<5 nm) MoO3 layers give rise to an 1.9 eV large interface dipole and a downwards bending of the MoO3 conduction band towards the Fermi level of graphene, leading to a near ideal alignment of the transport levels. The surface charge transfer manifests itself also as strong and stable p-type doping of the graphene layers, with the Fermi level downshifted by 0.25 eV and sheet resistance values consistently below 50 Ω/sq for few-layer graphene films. The combination of stable doping and highly efficient charge extraction/injection allows the demonstration of simplified graphene-based OLED device stacks with efficiencies exceeding those of standard ITO reference devices.

The Influence of Intrinsic Strain Softening on Strain Localization in Polycarbonate: Modeling and Experimental Validation

Abstract: Intrinsic strain softening appears to be the main cause for the occurrence of plastic localization phenomena in deformation of glassy polymers. This is supported by the homogeneous plastic deformation behavior that is observed in polycarbonate samples that have been mechanically pretreated to remove (saturate) the strain softening effect. In this study, some experimental results are presented and a numerical analysis is performed simulating the effect of mechanical conditioning by cyclic torsion on the subsequent deformation of polycarbonate. To facilitate the numerical analysis of the mechanical rejuvenation effect, a previously developed model, the compressible Leonov model, is extended to describe the phenomenological aspects of the large strain mechanical behavior of glassy polymers. The model covers common observable features, like strain rate, temperature and pressure dependent yield, and the subsequent strain softening and strain-hardening phenomena. The model, as presented in this study, is purely single mode' (i.e., only one relaxation time is involved), and therefore it is not possible to capture the nonlinear viscoelastic pre-yield behavior accurately. The attention is particularly focused on the large strain phenomena. From the simulations it becomes clear that the preconditioning treatment removes the intrinsic softening effect, which leads to a more stable mode of deformation.

Short-range order and thermal stability in amorphous alloys

Abstract: Amorphous alloys of the types Zr1-xNix, Zr1-xCox, Zr1-xFex and Zr1-xCux were prepared by melt-spinning and studied by means of differential scanning calorimetry and X-ray diffraction. The crystallisation temperatures (Tx) and the activation energies for crystallisation ( Delta E) were determined. The former values were found to vary only slightly with concentration while the latter show a marked concentration dependence, which is particularly pronounced in Zr1-xNix. The occurrence of compositional short-range ordering (CSRO) in amorphous systems is discussed with respect to its consequences for the hole model proposed earlier. It is shown that the predictions of the hole model are only slightly affected by the occurrence of CSRO, owing to a gross cancellation of the effects of a decreasing hole formation enthalpy and decreasing configuration entropy. The relatively strong temperature dependence of the configurational entropy expected for alloy compositions with strong CSRO leads to an increase in the experimental values of the apparent activation energies. From the concentration dependence of the experimental activation energies indications can be obtained about the concentration dependence of CSRO. It appears that the regions with a maximum CSRO do not, in general, correspond to the concentrations at which intermetallic compounds occur, nor do they correspond in all cases to regions located around the deepest eutectic composition.