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31.
Kimberly Sablon Andrei Sergeev Nizami Vagidov Andrei Antipov John Little Vladimir Mitin 《Nanoscale research letters》2011,6(1):584
We analyze the effect of doping on photoelectron kinetics in quantum dot [QD] structures and find two strong effects of the built-in-dot charge. First, the built-in-dot charge enhances the infrared [IR] transitions in QD structures. This effect significantly increases electron coupling to IR radiation and improves harvesting of the IR power in QD solar cells. Second, the built-in charge creates potential barriers around dots, and these barriers strongly suppress capture processes for photocarriers of the same sign as the built-in-dot charge. The second effect exponentially increases the photoelectron lifetime in unipolar devices, such as IR photodetectors. In bipolar devices, such as solar cells, the solar radiation creates the built-in-dot charge that equates the electron and hole capture rates. By providing additional charge to QDs, the appropriate doping can significantly suppress the capture and recombination processes via QDs. These improvements of IR absorption and photocarrier kinetics radically increase the responsivity of IR photodetectors and photovoltaic efficiency of QD solar cells. 相似文献
32.
N. E. Arancibia R. V. Bogdanov R. A. Kuznetsov A. S. Sergeev V. B. Glushkova T. I. Panova 《Radiochemistry》2002,44(5):508-517
Immobilization of radioactive wastes (RW) containing large amounts of process alkalis in ceramic matrices based on acid and basic rocks is studied. Immobilizing characteristics of samples with an RW content of 15% are obtained. The best geoceramic matrices are characterized by the forward leaching rates with double-distilled water of 1 × 10-
4 and 1 × 10-
5 g cm-
2 day-
1 for Sr and Cs, respectively, and the steady-state leaching rate of about 2 × 10-
6 g cm-
2 day-
1. Possible fixation mechanisms of the radionuclides in the matrices studied are discussed. Comparative analysis of properties of the geoceramic matrices and borosilicate and some other existing matrices for RW immobilization makes it possible to recommend some kinds of the geoceramics as matrices for immobilization of nonfractionated intermediate- and high-level radioactive wastes. 相似文献
33.
Khazanov E Andreev N Palashov O Poteomkin A Sergeev A Mehl O Reitze DH 《Applied optics》2002,41(3):483-492
We present a comprehensive and systematic investigation of the fundamental physical limitations of Faraday isolation performance at high average powers that are due to thermally induced birefringence. First, the operation of various Faraday isolator designs by use of arbitrary orientation of cubic magneto-optic crystals is studied theoretically. It is shown that, for different Faraday isolator designs, different crystal orientations can optimize the isolation ratio. Second, thermo-optic and photoelastic constants for terbium gallium garnet crystals grown by different manufacturers were measured. Measurements of self-induced depolarization are made for various orientations of crystallographic axes. The measurements are in good agreement with our theoretical predictions. Based on our results, it is possible to select a crystal orientation that optimizes isolation performance at high average powers, resulting in a 5-dB enhancement over nonoptimized orientations. 相似文献
34.
S. I. Sergeev 《Automation and Remote Control》2002,63(6):919-925
An upper estimate and an iterative restriction algorithm for the reachability set for determining the optimal control for a class of multistep control processes are designed. 相似文献
35.
N. S. Ginzburg A. M. Malkin N. Yu. Peskov A. S. Sergeev 《Technical Physics Letters》2006,32(10):896-900
A new scheme of feedback in a free-electron maser (FEM), which is based on the mutual scattering of propagating and quasi-cutoff (trapped) modes on a periodic Bragg structure, is considered. The trapped mode makes possible self-excitation of the system, while the energy exchange in a stationary generation regime is almost entirely determined by the interaction with a synchronous propagating wave. Using the proposed method, it is possible to improve mode selectivity with respect to the transverse index and accordingly decrease the working wavelength. 相似文献
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