3,462 research outputs found
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 comparable to those expected at HL-LHC (about
ten years of running, with an integrated luminosity of 3000 fb) 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
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
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