48 research outputs found
Observation of defect complexes containing Ga vacancies in GaAsN
Positron annihilation spectroscopy was used to study GaAsN/GaAs epilayers. GaAsN layers were found to contain Ga vacancies in defect complexes. The density of the vacancy complexes increases rapidly to the order of 1018 cm−3 with increasing N composition and decreases after annealing at 700 °C. The anticorrelation of the vacancy concentration and the integrated photoluminescence intensity suggests that the Ga vacancy complexes act as nonradiative recombination centers.Peer reviewe
Vacancy Defects In O-Doped Gan Grown By Molecular-Beam Epitaxy: The Role Of Growth Polarity And Stoichiometry
Target chamber for a slow positron beam: optimization of count rate and minimization of backscattering effects
Abstract Positrons, which scatter back from the target and annihilate in chamber walls near the detectors, may cause a significant error in annihilation parameters. We have constructed a new UHV target chamber for slow positron beam studies. In our design special care has been taken to reduce the effect of backscattered positrons. Detector wells are designed for two-detector coincidence measurements and they are situated on both sides of the target. The distance of the wells from the target can be adjusted by simple manipulators. This enables optimization regarding the count rate and the rate of backscattered positrons hitting the detector wells. The magnetic field in front of the target is increased by permanent magnets situated behind the target. The increased magnetic field guides the backscattered positrons effectively away from the detectors. The increased magnetic field also focuses the beam spot strongly.
Mild and Efficient Synthesis of 2‐Indole‐2′‐oxazolines at Room Temperature—A Simple Access to Novel IndOX Ligands
Influence of the holding time of the deep cryogenic treatment on the strain hardening behavior of HY-TUF steel
Facile, Efficient Routes to Diverse Protected Thiols and to Their Deprotection and Addition to Create Functional Polymers by Thiol-Ene Coupling
PyOX-ligands: the asymmetric Henry reaction
Abstract: C 2 -dissymmetric PyOX-ligands have been applied to the asymmetric Henry reaction. This widely applicable reaction is easy to perform, requires no inert atmospheres or dry solvents, and gives good selectivities. By adjusting ligand side-chains, a significant impact on selectivities was observed
Synthesis of a novel carboxy functionalized PyOX-ligand
A short and convenient synthesis of a carboxy functionalized PyOX-core is presented. The carboxy functionality offers a wide variety of possibilities for further modification. In this paper, the core is functionalized with a mercapto tail.Peer reviewe