Deep levels in a-plane, high Mg-content MgxZn1-xO epitaxial layers grown by molecular beam epitaxy

Deep level defects in n-type unintentionally doped a-plane MgxZn1−xO, grown by molecular beam epitaxy on r-plane sapphire were fully characterized using deep level optical spectroscopy (DLOS) and related methods. Four compositions of MgxZn1−xO were examined with x = 0.31, 0.44, 0.52, and 0.56 together with a control ZnO sample. DLOS measurements revealed the presence of five deep levels in each Mg-containing sample, having energy levels of Ec − 1.4 eV, 2.1 eV, 2.6 V, and Ev + 0.3 eV and 0.6 eV. For all Mg compositions, the activation energies of the first three states were constant with respect to the conduction band edge, whereas the latter two revealed constant activation energies with respect to the valence band edge. In contrast to the ternary materials, only three levels, at Ec − 2.1 eV, Ev + 0.3 eV, and 0.6 eV, were observed for the ZnO control sample in this systematically grown series of samples. Substantially higher concentrations of the deep levels at Ev + 0.3 eV and Ec − 2.1 eV were observed in ZnO compared to the Mg alloyed samples. Moreover, there is a general invariance of trap concentration of the Ev + 0.3 eV and 0.6 eV levels on Mg content, while at least and order of magnitude dependency of the Ec − 1.4 eV and Ec − 2.6 eV levels in Mg alloyed samples

Electrical Characterization of a Thin Edgeless N-on-p Planar Pixel Sensors For ATLAS Upgrades

In view of the LHC upgrade phases towards the High Luminosity LHC (HL-LHC), the ATLAS experiment plans to upgrade the Inner Detector with an all-silicon system. Because of its radiation hardness and cost effectiveness, the n-on-p silicon technology is a promising candidate for a large area pixel detector. The paper reports on the joint development, by LPNHE and FBK of novel n-on-p edgeless planar pixel sensors, making use of the active trench concept for the reduction of the dead area at the periphery of the device. After discussing the sensor technology, and presenting some sensors' simulation results, a complete overview of the electrical characterization of the produced devices will be given.Comment: 9 pages, 9 figures, to appear in the proceedings of the 15th International Workshops on Radiation Imaging Detector

Novel Silicon n-on-p Edgeless Planar Pixel Sensors for the ATLAS upgrade

In view of the LHC upgrade phases towards HL-LHC, the ATLAS experiment plans to upgrade the Inner Detector with an all-silicon system. The n-on-p silicon technology is a promising candidate for the pixel upgrade thanks to its radiation hardness and cost effectiveness, that allow for enlarging the area instrumented with pixel detectors. We report on the development of novel n-in-p edgeless planar pixel sensors fabricated at FBK (Trento, Italy), making use of the "active edge" concept for the reduction of the dead area at the periphery of the device. After discussing the sensor technology and fabrication process, we present device simulations (pre- and post-irradiation) performed for different sensor configurations. First preliminary results obtained with the test-structures of the production are shown.Comment: 6 pages, 5 figures, to appear in the proceedings of the 9th International Conference on Radiation Effects on Semiconductor Materials Detectors and Device

Development of Edgeless n-on-p Planar Pixel Sensors for future ATLAS Upgrades

The development of n-on-p "edgeless" planar pixel sensors being fabricated at FBK (Trento, Italy), aimed at the upgrade of the ATLAS Inner Detector for the High Luminosity phase of the Large Hadron Collider (HL-LHC), is reported. A characterizing feature of the devices is the reduced dead area at the edge, achieved by adopting the "active edge" technology, based on a deep etched trench, suitably doped to make an ohmic contact to the substrate. The project is presented, along with the active edge process, the sensor design for this first n-on-p production and a selection of simulation results, including the expected charge collection efficiency after radiation fluence of $1 \times 10^{15} {\rm n_{eq}}/{\rm cm}^2$ comparable to those expected at HL-LHC (about ten years of running, with an integrated luminosity of 3000 fb$^{-1}$) for the outer pixel layers. We show that, after irradiation and at a bias voltage of 500 V, more than 50% of the signal should be collected in the edge region; this confirms the validity of the active edge approach.Comment: 20 pages, 9 figures, submitted to Nucl. Instr. and Meth.

Performance of Irradiated Thin Edgeless N-on-P Planar Pixel Sensors for ATLAS Upgrades

In view of the LHC upgrade phases towards the High Luminosity LHC (HL-LHC), the ATLAS experiment plans to upgrade the Inner Detector with an all-silicon system. Because of its radiation hardness and cost effectiveness, the n-on-p silicon technology is a promising candidate for a large area pixel detector. The paper reports on the joint development, by LPNHE and FBK of novel n-on-p edgeless planar pixel sensors, making use of the active trench concept for the reduction of the dead area at the periphery of the device. After discussing the sensor technology, a complete overview of the electrical characterization of several irradiated samples will be discussed. Some comments about detector modules being assembled will be made and eventually some plans will be outlined.Comment: 6 pages, 13 figures, to appear in the proceedings of the 2013 Nuclear Science Symposium and Medical Imaging Conference. arXiv admin note: text overlap with arXiv:1311.162

Single phase a-plane MgZnO epilayers for UV optoelectronics: substitutional behaviour of Mg at large contents

High quality 1 μm thick a-plane MgxZn1−xO layers were produced by molecular beam epitaxy with Mg contents higher than 50%. Resonant Rutherford backscattering spectrometry combined with ion channeling revealed a uniform growth in both composition and atomic order. The lattice-site location of Mg, Zn and O elements was determined independently, proving the substitutional behaviour of Mg in Zn-sites of the wurtzite lattice. X-Ray diffraction pole figure analysis also confirms the absence of phase separation. Optical properties at such high Mg contents were studied in Schottky photodiodes

Conjugate Gradient Method Applied to Cortical Imaging in EEG/ERP

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Differential selection pressures exerted by host resistance quantitative trait loci on a pathogen population: a case study in an apple × Venturia inaequalis pathosystem

Understanding how pathogens evolve according to pressures exerted by their plant hosts is essential for the derivation of strategies aimed at the durable management of resistant cultivars. The spectrum of action of the resistance factors in the partially resistant cultivars is thought to be an important determinant of resistance durability. However, it has not yet been demonstrated whether the pressures exerted by quantitative resistance are different according to their spectrum of action.To investigate selection pressures exerted by apple genotypes harbouring various resistance quantitative trait loci (QTLs) on a mixed inoculum of the scab disease agent, Venturia inaequalis, we monitored V. inaequalis isolate proportions on diseased apple leaves of an F1 progeny using quantitative pyrosequencing technology and QTL mapping. Broad-spectrum resistances did not exert any differential selection pressures on the mixed inoculum, whereas narrow-spectrum resistances decreased the frequencies of some isolates in the mixture relative to the susceptible host genotypes. Our results suggest that the management of resistant cultivars should be different according to the spectrum of action of their resistance factors. The pyramiding of broad-spectrum factors or the use of a mixture of apple genotypes that carry narrow-spectrum resistance factors are two possible strategies for the minimization of resistance erosion