Institute of Physical Technical Problems

Dubna, Russia

Institute of Physical Technical Problems

Dubna, Russia
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Polyakov A.Y.,Institute of Rare Metals | Smirnov N.B.,Institute of Rare Metals | Govorkov A.V.,Institute of Rare Metals | Lee I.-H.,Chonbuk National University | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Properties of GaN radiation detectors are analyzed. It is shown that present day epitaxial material is suitable for detection of α-particles with the charge collection efficiency close to 100%. Such detectors can operate at temperatures of at least 60°C and withstand irradiation with reactor neutrons fluences higher than 1015 cm-2. They keep the collection efficiency at 30% even after irradiation with 2×1016 cm-2 neutron fluence. Registration of thermal neutrons with GaN detectors can also be achieved by using 10B converter and the efficiency of registration is determined by the 10B conversion efficiency from neutrons to low energy a-particles. © 2011 SPIE.

Lee I.-H.,Chonbuk National University | Polyakov A.Y.,Chonbuk National University | Polyakov A.Y.,Institute of Rare Metals | Smirnov N.B.,Institute of Rare Metals | And 6 more authors.
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics | Year: 2012

Electrical properties and deep electron and hole trap spectra were measured for undoped n-GaN cut from a thick boule grown by hydride vapor phase epitaxy (HVPE). The material is characterized by a very low concentration of residual donors (1013-1014cm-3) in the first 30 m near the growth surface. The bulk electrical properties were similar to those of standard high quality undoped bulk HVPE n-GaN, with a net donor concentration of ∼1016cm-3 and mobility ∼1000 cm2/V s. The strong decrease of electron concentration in the surface region of the high resistivity GaN was caused by the compensation of shallow residual donors by a high density (∼6 1015cm-3) of hole traps with activation energy of 0.2 eV, confined to the compensated region. In addition, other hole traps H5 with activation energy 1.2 eV and concentration 5 10 15cm-3 were present. These latter traps had similar concentrations in both the high resistivity and standard conducting HVPE GaN. Radiation detectors prepared on the high resistivity material showed charge collection efficiency (CCE) close to 100 for spectrometry of -particles with energy up to 5.1 MeV. The CCE dependence on voltage indicated a strong trapping of holes in the active region of detectors by the H5 hole traps. © 2012 American Vacuum Society.

Khlebnikov I.B.,Institute of Physical Technical Problems | Khudykh G.V.,Institute of Physical Technical Problems | Smirnov A.A.,Institute of Physical Technical Problems | Priladyshev A.A.,Joint Institute for Nuclear Research | And 3 more authors.
Atomic Energy | Year: 2013

The evolution of domestic designs of nitrogen-free spectrometers with microcryogenic cooling systems with semiconductor detectors based on ultrapure germanium is examined. The energy resolution of a monoblock germanium nitrogen-free spectrometer with a microcryogenic system and digital spectrometric setup, built at the Institute of Physical-Technical Problems, is 2.25 keV on the 1.33 MeV line. Nitrogen-free spectrometers have proven themselves well in mobile and stationary laboratories providing fast analysis and at technological checkpoints in NPP. © 2013 Springer Science+Business Media New York.

Gazizov I.M.,Institute of Physical Technical Problems | Zaletin V.M.,Dubna University | Govorkov A.V.,State Research and Project Institute of Rare Metal Industry GIREDMET | Kuznetsov M.S.,State Research and Project Institute of Rare Metal Industry GIREDMET | And 3 more authors.
Semiconductors | Year: 2014

TlBr is a promising wide-gap semiconductor for developing γ-radiation detectors. One of the limiting factors in developing the technology of detectors is the lack of experimentally determined trapping and recombination centers. In this paper, a generalized model of the formation and behavior of intrinsic defects in pure and doped TlBr single crystals is presented. The relation of intrinsic defects to growth conditions and electrical properties is determined. The previously obtained temperature dependences of the photoconductivity, the data of current deep level transient spectroscopy and microcathodoluminescence, and the kinetic characteristics of the photoconductivity are used as objects of analysis. It is shown that the compensation of charged centers control the transport properties of charge carriers. In compensated doped TlBr crystals, the product of the mobility and lifetime can reach μτ = 5 × 10-4 cm2 V-1. The energy-level diagram of local levels in pure and doped TlBr crystals is proposed. The ionization energies of major structural and impurity defects in TlBr, i.e., the anion vacancy V a +, cation vacancy V c -, and Pb2+, O2-, S2- ions, are determined. The energy position of a single anion vacancy Va + is E c - 0.22 eV. The energy level of the cation vacancy is E v + 0.85 eV for a single cation vacancy and E v + 0.58 eV for a vacancy incorporated into the {Pb2+ V c -}0 complex. The ionization energy of the Pb2+ Coulomb trap is E c - 0.08 eV in doped TlBr crystals. © 2014 Pleiades Publishing, Ltd.

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