Application of the method of differential inequalities for the justification of the asymptotic of solution of a system of two ordinary differential equations in the form of step type contrasting structure.
Application of the method of differential inequalities for the justification of the asymptotic of solution of a system of two ordinary differential equations in the form of step type contrasting structure.
N.T. Levashova, E.S. Petrovskaya
An asymptotic expansion of the solution of a boundary value problem for a system of two ordinary differential equations in the form of step-type contrasting structures was built. Using the method of differential inequalities, was proved the existence of the considered problems of decisions of this type, for which the built decomposition is constructed asymptotic approximation.
Show AbstractSome russian scientific achievements in optoelectronics
Some russian scientific achievements in optoelectronics
O. I. Rabinovich
Review of Russian scientific achievements in developing optoelectronic devices over more than 100 years is presented.
Show AbstractStudy of charge relaxation processes in quantum wells of InGaN/GaN MQW LEDs using frequency dependences of capacitance and conductance
Study of charge relaxation processes in quantum wells of InGaN/GaN MQW LEDs using frequency dependences of capacitance and conductance
Soltanovich O.A. Yakimov E.B.
Capacitance-frequency and conductance-frequency dependences for InGaN/GaN multiple-quantum-well light-emitting structures are investigated at wide ranges of temperature and bias voltage. The charge relaxation in a quantum well is found to be satisfactorily described by two emission processes with different dependences of emission rate on temperature. It is shown that in typical InGaN/GaN light-emitting structures, one or a few quantum wells can be filled with electrons even for the relatively high reverse biases applied to the structure and contribute to the measured capacitance. This allows to explain the observed temperature and frequency dependences of apparent carrier concentration profiles obtained under capacitance—voltage profiling in these structures.
Show AbstractEfficiency of GaN light-emitting diodes and carrier energetic relaxation in InGaN/GaN quantum wells
Efficiency of GaN light-emitting diodes and carrier energetic relaxation in InGaN/GaN quantum wells
N.I. Bochkareva, V.V. Voronenkov, Y.T. Rebane, Y.G. Shreter
A direct correlation is found between efficiency droop and changes in the high energy side of emission spectrum of InGaN/GaN quantum wells (QWs) with increasing current density. A dynamic model of energy relaxation of injected carriers in exponential band tails of InGaN QWs is proposed. At low injection level the carriers trapped by shallow tail states quickly hop directly to lower-energy tail states. This results in the strong carrier localization and high-energy cutoff of emission spectrum. At higher injection level hopping directly to deeper states is suppressed due to the partial filling of tail states. As a result the ratio of mobile to localized carriers increases with current. The emission efficiency decreases because of the enhancement of lateral diffusion length, carrier capture by defects and tunnel-recombination leakage via defects. Simultaneously the high-energy cutoff of emission spectrum shifts to higher energy. Thus, the magnitude of efficiency droop is directly related to the relative broadening of emission spectrum.
Show AbstractRegularities and features of current dependences of junction-case thermal resistance of InGaN/GaN power light-emitting diodes
Regularities and features of current dependences of junction-case thermal resistance of InGaN/GaN power light-emitting diodes
Sergeev V.A. Smirnov V.I. Frolov I.V. Hodakov A.M.
On the basis of measurement of thermal characteristics on 30 sampels of power InGaN/GaN light emitting diodes (LED) of Cree production of in the range of current 50... 550 mА it is shown that thermal resistance junction-case of all LEDs increases with increase of working current. It is established that the steepness of current dependence of consid-erably decreases at currents more than 300 mА. Selective parameters of current de-pendences are calculated. The received results confirm adequacy of early offered nonlinear thermal models of power LED and can use for an estimating of heterogeneity of distribution of temperature and current density in LED's structures.
Show AbstractPhase velocity of space-charge waves in n-InN, n-GaN and n-AlN semiconductor struc-tures
Phase velocity of space-charge waves in n-InN, n-GaN and n-AlN semiconductor struc-tures
S.A. Sergeev, A.I. Mikhailov, O.S. Senatov, B.V. Sergeeva
Some results of theoretical investigation of the influence of diffusion and frequency dispersion of electrons differential mobility on the phase velocity of space-charge waves propagating in drift beam of electrons in semiconductor structures of indium nitride, gallium nitride and aluminum nitride are given in the paper
Show AbstractThe perspectives of gallium, indium and aluminium nitrides application for functional devices on space charge waves
The perspectives of gallium, indium and aluminium nitrides application for functional devices on space charge waves
S.A. Sergeev, A.I. Mikhailov, B.V. Sergeeva
The analysis of modern reference data for AlN, InN, GaN parameters and characteristics in comparison with GaAs ones for investigation of realization perspectives of devices on space charge waves was carried out in the work.
Show AbstractMaskless structuring of the surface of silicon substrates for nitride epitaxy
Maskless structuring of the surface of silicon substrates for nitride epitaxy
M.G. Mynbaeva, S.P. Lebedev, A.A. Lavrent'ev, K.D. Mynbaev, V.I. Nikolaev
A self-structuring of the surface of silicon wafers under specific annealing conditions is reported on. This effect can be used for developing new maskless methods of the fabrication of structured silicon substrates, which are prospective for the use in the technology of light-emitting diodes based on gallium nitride and III–nitride solid solutions.
Show AbstractCharacterization of GaN and GaN based structures by scanning electron microscopy methods
Characterization of GaN and GaN based structures by scanning electron microscopy methods
Yakimov E.B.
Results demonstrating possibilities of scanning electron microscopy methods for a characterization of GaN and GaN based light emitting structures are presented. Methods for correct excess carrier diffusion length measurementы in the structures with the small diffusion length are discussed. It is shown that the Electron Beam Induced Current (EBIC) method allows not only to measure the diffusion length in GaN films but in some cases to reconstruct also the lateral donor center distribution with a spatial resolution in the micrometer range. It is shown experimentally that in the structures with the small diffusion length the lateral resolution under extended defects revealing can be about 100 nm or even better. It is shown that channels of enhanced minority carrier transport across the active region of light emitting structures with InGaN/GaN quantum wells can be revealed by the EBIC.
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