3,414 research outputs found
Three-dimensional charge transport mapping by two-photon absorption edge transient-current technique in synthetic single-crystalline diamond
We demonstrate the application of two-photon absorption transient current
technique to wide bandgap semiconductors. We utilize it to probe charge
transport properties of single-crystal Chemical Vapor Deposition (scCVD)
diamond. The charge carriers, inside the scCVD diamond sample, are excited by a
femtosecond laser through simultaneous absorption of two photons. Due to the
nature of two-photon absorption, the generation of charge carriers is confined
in space (3-D) around the focal point of the laser. Such localized charge
injection allows to probe the charge transport properties of the semiconductor
bulk with a fine-grained 3-D resolution. Exploiting spatial confinement of the
generated charge, the electrical field of the diamond bulk was mapped at
different depths and compared to an X-ray diffraction topograph of the sample.
Measurements utilizing this method provide a unique way of exploring spatial
variations of charge transport properties in transparent wide-bandgap
semiconductors.Comment: This article may be downloaded for personal use only. Any other use
requires prior permission of the author and AIP Publishing. The following
article appeared in Applied Physics Letters and may be found at
https://doi.org/10.1063/1.509085
Sensor Simulation and position calibration for the CMS pixel detector
In this paper a detailed simulation of irradiated pixel sensors was used to
investigate the effects of radiation damage on charge sharing and position
determination. The simulation implements a model of radiation damage by
including two defect levels with opposite charge states and trapping of charge
carriers. We show that charge sharing functions extracted from the simulation
can be parameterized as a function of the inter-pixel position and used to
improve the position determination. For sensors irradiated to Phi=5.9x10^14
n/cm^2 a position resolution below 15 um can be achieved after calibration.Comment: Presented at the 14th Int. Workshop on Vertex Detectors (Vertex
2005), November 7-11 2005, Chuzenji Lake, Nikko, Japan. 4 pages, 1 figur
Pyridazines Lil. Polychloro Pyrido(2,3-d)- and -(3,4-d)pyridazines
The successful synthesis of perchloroimidazo(l,2-b)pyridazine1 prompted
us to investigate the possibility .of preparing chlorinated pyridopyridazines.
Although both parent bicyclic systems (I, II) are not expected to be susceptible to electrophilic substitution, pyrido(2,3-d)pyridazine, when brominated, formed primarily a complex which upon pyrolysis at 170- 180° is transformed into the 3-bromo derivative2
Pyridazines Lil. Polychloro Pyrido(2,3-d)- and -(3,4-d)pyridazines
The successful synthesis of perchloroimidazo(l,2-b)pyridazine1 prompted
us to investigate the possibility .of preparing chlorinated pyridopyridazines.
Although both parent bicyclic systems (I, II) are not expected to be susceptible to electrophilic substitution, pyrido(2,3-d)pyridazine, when brominated, formed primarily a complex which upon pyrolysis at 170- 180° is transformed into the 3-bromo derivative2
Diameter selective characterization of single-wall carbon nanotubes
A novel method is presented which allows the characterization of diameter
selective phenomena in SWCNTs. It is based on the transformation of fullerene
peapod materials into double-wall carbon nanotubes and studying the diameter
distribution of the latter. The method is demonstrated for the diameter
selective healing of nanotube defects and yield from C peapod samples.
Openings on small diameter nanotubes are closed first. The yield of very small
diameter inner nanotubes from C peapods is demonstrated. This challenges
the theoretical models of inner nanotube formation. An anomalous absence of
mid-diameter inner tubes is observed and explained by the suppressed amount of
C peapods due to the competition of the two almost equally stable
standing and lying C peapod configurations
Bias dependence and bistability of radiation defects in silicon
Influence of bias on effective dopant concentration in neutron and pion irradiated diodes has been measured. Detailed studies of annealing of the bias-induced damagehave revealed three components, with introduction rates from 0.005 to 0.008 cm andannealing time constants ranging from 5 to 1000 hours at 20C. Variation of annealing temperatures yielded activation energies around 1 eV for all the three components. Bistable behavior of radiation damage under bias has been observed and its activation and annealingstudied. The bistable damage was associated to the fastest annealing component of bias-induced damage.Using the parameterization obtained, a prediction for ATLAS SCT operation was made.Bias-induced damage is shown to require an additional 80 V to fully deplete detectors at the end of LHC operation
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