1,720,997 research outputs found
Transport Properties of Bi_2Sr_2CuO_{6+delta}_m/(CaCuO_2)_nMultilayers obtained by Molecular Beam Epitaxy
No full textEffects of the post oxygenation process on RHEED patterns in MBE grown YBa2Cu3O7-x thinfilms
No full textOptical properties of ionic liquid passivated CdSe/ZnS quantum dots dispersed in POC copolymer
No full textA new blue emitter oxadiazole/carbazole copolymer has been synthesized and combined with CdSe/ZnS quantum dots (QDs). Surface passivation of the QDs by ionic liquids was crucial to improve their compatibility with the polymer allowing the deposition of homogeneous nanocomposites films. The nanocomposites have been characterized by thermogravimetric analysis, infrared, UV–visible absorption, and photoluminescence spectroscopy. The emission spectra of nanocomposites show a wide spectrum from blue to orange wavelengths due to the combination of colors emitted by the polymer and QDs, respectively. POLYM. COMPOS., 34:1471–1476, 2013. © 2013 Society of Plastics Engineer
Morphology and crystallinity of homoepitaxial (100)ZnTe: interplay between surface ad-atom stoichiometry and planar defects nucleation during MOVPE
No full textThe morphology and structure of metalorganic vapour phase epitaxy grown homoepitaxial (1 0 0)ZnTe layers on
high-quality substrates grown by the vertical gradient freezing method is reported. Growth below 350 °C leads to surface ridging along a 110 in-plane direction of the epilayer, the morphology of samples grown at or above 350 °C depending instead on the Te:Zn ad-atom relative abundance. Nearly featureless morphology is observed for epilayers grown under Zn-rich or nearly stoichiometric surface conditions, whereas large pyramid-like hillocks develop on Terich
surfaces, their density reaching up to 106 – 107 cm2. Hillock formation is supposed to be driven by Te ad-atoms experiencing a Schwoebel potential barrier at the step edges around spiral centres, the latter ascribed to partial dislocation pairs bounding stacking faults (SFs). Analysis of the X-ray diffuse scattering intensity around the (4 0 0)
reciprocal lattice point of the samples demonstrates that SFs occur in epilayers grown at or above 350 °C, their density
increasing with the growth temperature. The SF average diameter on {1 1 1} planes is estimated as 200–300 nm
Fabrication of superconducting Nd2−xCexCuO4±δ films by automated dc sputtering technique
No full textThe Resistive Anomaly and Upward Curvature of the PerpendicularUpper Critical Field in Nonhomogeneous Superconductors
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Structural characterization of ZnSe/ZnMgSe MQWs grown on (100)GaAs by low pressure MOVPE
No full textA detailed structural characterization of ZnSe/ZnMgSe multiple quantum wells (MQWs) grown on GaAs by low pressure metalorganic vapour phase epitaxy is presented. ZnSe/Zn0.83Mg0.17Se MQWs having between 6 and 12 periods were deposited at 330°C and 304 mbar reactor pressure on (100)GaAs after a 4.2 nm ZnSe buffer layer. The MQWs had nominal 4.4 nm thick ZnSe wells and 53 nm thick Zn(0.83)Ma(0.17)Se barriers. The MQW structural properties were investigated by high-resolution X-ray diffraction (HRXRD) and X-ray specular reflectivity (XSR) measurements, besides the MQWs-substrate mismatch. Simulation of the HRXRD and XSR patterns allowed to determine the MQW period, individual layer thickness and barrier composition. Between 8 and 10 periods the MQW structure begins to relax. its critical thickness on GaAs being between 92 and 113 nm. Furthermore, HRXRD showed broader zeroth and first-order satellite peaks with increasing MQW periods, a result ascribed to strain fluctuations induced by either inhomogeneous Mg incorporation in the ZnSe lattice and/or interface roughening. Comparison or experimental and simulated XSR patterns allowed to determine the rms roughness at each multilayer interface, which linearly increases along the growth direction due to a cumulative intrinsic roughening
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