A. N. Zarubin
Tomsk State University
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Publication
Featured researches published by A. N. Zarubin.
Journal of Instrumentation | 2014
D Pennicard; S Smoljanin; B. Struth; H Hirsemann; A. Fauler; M. Fiederle; O. P. Tolbanov; A. N. Zarubin; A. V. Tyazhev; G Shelkov; H Graafsma
Many X-ray experiments at third-generation synchrotrons benefit from using single-photon-counting detectors, due to their high signal-to-noise ratio and potential for high-speed measurements. LAMBDA (Large Area Medipix3-Based Detector Array) is a pixel detector system based on the Medipix3 readout chip. It combines the features of Medipix3, such as a small pixel size of 55 μm and flexible functionality, with a large tileable module design consisting of 12 chips (1536 × 512 pixels) and a high-speed readout system capable of running at 2000 frames per second. To enable high-speed experiments with hard X-rays, the LAMBDA system has been combined with different high-Z sensor materials. Room-temperature systems using GaAs and CdTe systems have been produced and tested with X-ray tubes and at synchrotron beamlines. Both detector materials show nonuniformities in their raw image response, but the pixel yield is high and the uniformity can be improved by flat-field correction, particularly in the case of GaAs. High-frame-rate experiments show that useful information can be gained on millisecond timescales in synchrotron experiments with these sensors.
Journal of Instrumentation | 2014
D.L. Budnitsky; A. V. Tyazhev; V. A. Novikov; A. N. Zarubin; O. P. Tolbanov; M. S. Skakunov; Elias Hamann; A. Fauler; Michael Fiederle; S. Procz; H Graafsma; S Ryabkov
Results obtained from numerical calculations of and experimental studies on the pulse height distribution inherent in ionizing radiation gallium arsenide sensors as a function of the design features of the devices and electrophysical characteristics of the detector material are presented. It is shown that the pulse height distribution is defined by the distribution pattern of the nonequilibrium charge carrier lifetime and by the electric field profile in the bulk of the sensor. Investigations on the detector sensitivity to X-ray energies in the range between 40 and 150 keV were performed. The sensor polarization was found to produce only a marginal effect compensated by an increase in the bias voltage. Prototype pixel sensors measuring 256 × 256 and 512 × 768 pixels with a 55 μm pitch and a 500 μm thick sensitive layer were produced. The dependence of the photocurrent and count rate on the X-ray radiation intensity and bias voltage applied to the sensor was examined. In the 40–80 keV energy range, the maximum count rate amounted to 800 kHz/pixel for a negative sensor bias voltage of 800 V. The sensors are demonstrated to provide spatial resolution varying with the pixel pitch and to enable high-quality X-ray images to be obtained.
Semiconductors | 2011
V. M. Kalygina; A. N. Zarubin; Ye. P. Nayden; V. A. Novikov; Yu. S. Petrova; O. P. Tolbanov; A. V. Tyazhev; T. M. Yaskevich
The effect of oxygen plasma on gallium oxide films formed by electrochemical oxidation of n-GaAs wafers with a donor concentration Nd = (1–2) × 1016 cm−3 has been investigated. It is shown that the treatment in an oxygen plasma at a temperature of 50–90°C increases the concentration of β-phase crystallites, which causes an increase in the permittivity, a decrease in the dielectric dissipation factor, and a change in the conductivity of GaAs-〈gallium oxide〉-metal structures.
Journal of Instrumentation | 2014
Matthew C. Veale; S.J. Bell; D.D. Duarte; M.J. French; M. Hart; Andreas Schneider; P. Seller; Matthew D. Wilson; V Kachkanov; A. Lozinskaya; V. A. Novikov; O. P. Tolbanov; A. V. Tyazhev; A. N. Zarubin
Semi-insulating wafers of GaAs material with a thickness of 500μm have been compensated with chromium by Tomsk State University. Initial measurements have shown the material to have high resistivity (3 × 109Ωcm) and tests with pixel detectors on a 250 μm pitch produced uniform spectroscopic performance across an 80 × 80 pixel array. At present, there is a lack of detectors that are capable of operating at high X-ray fluxes (> 108 photons s-1 mm-2) in the energy range 5–50 keV. Under these conditions, the poor stopping power of silicon, as well as issues with radiation hardness, severely degrade the performance of traditional detectors. While high-Z materials such as CdTe and CdZnTe may have much greater stopping power, the formation of space charge within these detectors degrades detector performance. Initial measurements made with GaAs:Cr detectors suggest that many of its material properties make it suitable for these challenging conditions. In this paper the radiation hardness of the GaAs:Cr material has been measured on the B16 beam line at the Diamond Light Source synchrotron. Small pixel detectors were bonded to the STFC Hexitec ASIC and were irradiated with 3 × 108 photons s-1 mm-2 monochromatic 12 keV X-rays up to a maximum dose of 0.6 MGy. Measurements of the spectroscopic performance before and after irradiation have been used to assess the extent of the radiation damage.
Semiconductors | 2010
V. M. Kalygina; A. N. Zarubin; V. A. Novikov; Yu. S. Petrova; M. S. Skakunov; O. P. Tolbanov; A. V. Tyazhev; T. M. Yaskevich
The effect of oxygen plasma on the leakage current, permittivity, and the dielectric loss tangent of Ta2O5 thin layers (300–400 nm) is studied. It is suggested to treat tantalum oxide films in oxygen plasma to control their electrical and dielectric characteristics.
Semiconductors | 2013
V. M. Kalygina; A. N. Zarubin; V. A. Novikov; Yu. S. Petrova; O. P. Tolbanov; A. V. Tyazhev; S. Yu. Tsupiy; T. M. Yaskevich
The current-voltage (I–V), capacitance-voltage (C–V), and conductance-voltage (G–V) characteristics of metal/GaxOy/GaAs/metal structures are investigated. Gallium-oxide films with a thickness of 150–170 nm are deposited by the thermal evaporation of Ga2O3 powder onto n-type GaAs substrates with the donor concentration Nd = 2 × 1016 cm−3. Treatment of the GaxOy films in oxygen plasma causes a decrease in both the forward and reverse currents and a shift of the C–V and G–V curves to higher positive voltages. The Fermi level at the insulator/semiconductor interface in the structures under study is unpinned. The density of states at the GaxOy/GaAs interface is Nt = (2–6) × 1012 eV−1 cm−2.
Semiconductors | 2012
V. M. Kalygina; K. I. Valiev; A. N. Zarubin; Yu. S. Petrova; O. P. Tolbanov; A. V. Tyazhev; T. M. Yaskevich
The influence of oxygen plasma and thermal annealing at 900°C on the capacitance-voltage and conductivity-voltage characteristics of n-GaAs-(anodic oxide)-metal structures is studied. In contrast to the unannealed structures, high-temperature annealing in Ar for 30 min leads to the emergence of a voltage dependence of the capacitance (C) and conductivity (G). The influence of oxygen plasma on a Ga2O3 film before annealing promotes additional variation in the capacitance-voltage and conductivity-voltage characteristics.
Journal of Instrumentation | 2017
Matthew C. Veale; P. Booker; B. Cline; J. Coughlan; M. Hart; T. Nicholls; Andreas Schneider; P. Seller; I. Pape; K. Sawhney; A. Lozinskaya; V. A. Novikov; O. P. Tolbanov; A. V. Tyazhev; A. N. Zarubin
The STFC Rutherford Appleton Laboratory (U.K.) and Tomsk State University (Russia) have been working together to develop and characterise detector systems based on chromium-compensated gallium arsenide (GaAs:Cr) semiconductor material for high frame rate X-ray imaging. Previous work has demonstrated the spectroscopic performance of the material and its resistance to damage induced by high fluxes of X-rays. In this paper, recent results from experiments at the Diamond Light Source Synchrotron have demonstrated X-ray imaging with GaAs:Cr sensors at a frame rate of 3.7 MHz using the Large Pixel Detector (LPD) ASIC, developed by STFC for the European XFEL. Measurements have been made using a monochromatic 20 keV X-ray beam delivered in a single hybrid pulse with an instantenous flux of up to ~ 1 × 1010 photons s−1 mm−2. The response of 500 μm GaAs:Cr sensors is compared to that of the standard 500 μm thick LPD Si sensors.
Semiconductors | 2013
V. M. Kalygina; V. V. Vishnikina; A. N. Zarubin; V. A. Novikov; Yu. S. Petrova; O. P. Tolbanov; A. V. Tyazhev; S. Y. Tcupiy; T. M. Yaskevich
The effect of the annealing temperature on the I–V, C–I, and G–V characteristics and transparency of gallium-oxide films is investigated. The films are fabricated by the thermal evaporation of Ga2O3 powder on n-GaAs wafers. It is shown that the films which are amorphous after deposition crystallize upon annealing at temperatures Tan ≥ 800°C. The electrical characteristics and photoresponse of the V/Ni-GaAs-GaAs-GaxOy-V/Ni samples to visible radiation depend on the structure and phase composition of the films.
Journal of Instrumentation | 2018
M. Ruat; M. Andrä; A. Bergamaschi; R. Barten; M. Brückner; R. Dinapoli; Erik Fröjdh; D. Greiffenberg; C. Lopez-Cuenca; A. Lozinskaya; D. Mezza; A. Mozzanica; V. A. Novikov; M. Ramilli; S. Redford; C. Ruder; B. Schmitt; X. Shi; D. Thattil; G. Tinti; O. P. Tolbanov; A. V. Tyazhev; S. Vetter; A. N. Zarubin; J. Zhang
High-Z sensors are increasingly used to overcome the poor efficiency of Si sensors above 15 keV, and further extend the energy range of synchrotron and FEL experiments. Detector-grade GaAs sensors of 500 μm thickness offer 98% absorption efficiency at 30 keV and 50% at 50 keV . In this work we assess the usability of GaAs sensors in combination with the MYTHEN photon-counting microstrip readout chip developed at PSI. Different strip length and pitch are compared, and the detector performance is evaluated in regard of the sensor material properties. Despite increased leakage current and noise, photon-counting strips mounted with GaAs sensors can be used with photons of energy as low as 5 keV, and exhibit excellent linearity with energy. The charge sharing is doubled as compared to silicon strips, due to the high diffusion coefficient of electrons in GaAs.