Publications on the project |
007 Lateral transport and far Infrared emission of electrons in the InxGa1−x As/GaAs heterostructures with double tunnel-coupled quantum wells under a strong electric field |
Authors: | N.V.Baidus, P.A.Belevskii, A.A.Biriukov, V.V. Vainberg, M.N. Vinoslavskii, A.V.Ikonnikov, B.N. Zvonkov, A.S. Pylypchuk, V.N.Poroshin | |
Summary: | It is shown that far infrared emission of hot electrons in selectively doped heterostructures with double tunnel-coupled quantum wells under strong lateral electric fields significantly dependens on the doping level in the wells. In the case of high impurity concentration in the narrower well, more than (1−2) 1011cm−2, emission is caused only by indirect intrasub-band transitions of electrons. At lower impurity concentrationsalong with the indirect transitions a contribution to emission isgiven by the direct intersubband transitions of electrons whichbecome possible under strong electric fields in consequence ofthe real space transfer of electrons between quantum wells. | |
Keywords: | Heterostructures, quantum wells, lateral transport, hot electrons, infrared radiation | |
Edition: | Semiconductors | | | 2010,
4,Russian |
007 Transport properties of InGaAs/GaAs heterostructures with δ-doped quantum wells |
Authors: | N.V. Baidus, V.V. Vainberg, B.N. Zvonkov, A.S. Pylypchuk, V.N. Poroshin, O.G. Sarbey | |
Summary: | The lateral transport in pseudomorphous heterostructures GaAs/InGaAs/GaAs with 50 to 100 meV deep single as well as double quantum wells has been investigated. The wells were δ-doped with the impurity concentration of 1011 <Ns <1012 cm−2. For the single well structures one observes a non-monotonous temperature dependence of Hall coefficient and an increase of low-temperature electron mobility with increasing impurity concentration. The results obtained indicate an important role of the conductivity in the impurity band. Consideration of the impurity band in the quantum well enables to explain the conductance characteristics of the double structures, as well. Besides, in these structures the band bending due to asymmetric doping also strongly influences the electron conductivity. Numerical calculations of the conductivity confirm the suggested model. | |
Keywords: | Heterostructures, quantum wells, lateral transport, hot electrons, galvano-magnetic properties | |
Edition: | Semiconductors | | | 2012,
6,Russian |
007 Electron mobility in the GaAs/InGaAs/GaAs quantum wells |
Authors: | V.V. Vainberg, A.S. Pylypchuk, N.V. Baidus, B.N. Zvonkov | |
Summary: | The temperature dependence of the electron lateral mobility in quantum wells of the GaAs/InGaAs/GaAs heterostructures with delta-like doping has been studied. Two types of sample doping – in the quantum well and in the adjacent barrier at a small distance from the well – were used. In the case of shallow wells, in such structures the experimental results may be well described by known electron scattering mechanisms taking into account the shape of real envelope wave functions and band bending due to non-uniform distribution of the positive and negative space charges along the growth direction of heterostructure layers. In the case of delta-like doping in the well, a good agreement between experiment and calculations is achieved, if one takes into account a contribution to electron transport of the states of the impurity band formed by the delta-impurity beneath the bottom of the lowest quantum subband. | |
Keywords: | Heterostructures, quantum wells, lateral transport, hot electrons, galvano-magnetic properties | |
Edition: | Semiconductor Physics, Quantum Electronics & Optoelectronics | | | 2013,
10,English |
007 Features of magnetoresistance in the heterostructures with selectively doped quantum wells |
Authors: | V.V.Vainberg, A.S.Pylypchuk, V.N.Poroshin | |
Summary: | The field dependence of the low-temperature (T=4.2 K) lateral magnetoresistance of quantum wells with selective doping in the wells is studied. The concentration of impurities within the quantum wells is changed in the range of (1–7) 1011 cm-2. The analysis of experimental results within the scope of the available theories of weak localization is carried out. A good agreement between theory and experiment at a sufficiently high concentration of impurities is obtained. The reasons for the disagreement at low concentrations are discussed. | |
Keywords: | Heterostructures, quantum well, lateral conduction, magnetoresistance, delta-doping | |
Edition: | Nanosystems, Nanomaterials, Nanotechnologies | | | 2014,
10,Russian |
007 Influence of conduction via a channel of an impurity δ-layer on the magneto-quantum effects in AlGaAs/GaAs/AlGaAs heterostructures |
Authors: | V.V. Vainberg, A.S. Pylypchuk, V.N. Poroshin, O.G. Sarbey, N.V. Baidus, A.A. Biryukov | |
Summary: | The lateral magnetoresistance of the multi-layer AlGaAs/GaAs/AlGaAs heterostructures with quantum wells and impurity δ-layers in the adjacent barriers has been studied at 4.2 K. It is shown that both the classical magnetoresistivity tensor components and the magneto-quantum effects in such structures considerably depend on the contribution to conduction from the channel with small mobility formed in the impurity δ-layer. The obtained results are analyzed within the frame of the model of electron transport via two parallel channels with different electron mobilities. Based on this model the electron concentration in both the structural and δ-layer quantum wells and the dependence of the components of the magnetoresistivity tensor, including the magneto-quantum effects, on magnetic field strength have been calculated for samples with different doping level and manifest a good agreement between experimental results and calculations. | |
Keywords: | Heterostructures, Quantum well, Selective doping, Magneto-quantum effects | |
Edition: | Physica E | | | 2014,
6,English |
007 Influence of narrow inner barriers on low-temperature lateral conduction in quantum wells |
Authors: | V.V. Vainberg, A.S. Pylypchuk, N.V. Baidus, A.A. Birukov | |
Summary: | The electron energy spectrum in a wide quantum well with different number of narrow barriers in it has been calculated. It is shown that the size quantization
levels are raised in energy with inserting such barriers. After a maximum filling of the quantum well by narrow barriers and the formation of a short-period super-
lattice fragment the wave functions envelop of the electrons at the size quantization levels are close in shape to those in a usual quantum well. In that case the scattering by heterojunctions surface roughness becomes more intensive. The low-temperature lateral conduction both in the quantum well which is tunnel-coupled with a 10- well short-period superlattice and in the superlattice has been investigated experimentally. The obtained results agree sufficiently well with model calculations and show a new possibility to create parallel conducting channels with different electron mobility.
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Keywords: | Heterostructures, superlattice, quantum well, lateral conduction | |
Edition: | Low Temperature Physics | | | 2014,
,Russian |
007 Effects of real-space transfer of charge carriers in the n-AlGaAs/GaAs heterostructures with the delta-layers of impurity in the barriers |
Authors: | V.V. Vainberg, A.S. Pylypchuk, V.N. Poroshin, O.G. Sarbey | |
Summary: | The results of investigations of the electric and magnetic transport phenomena of charge carriers in the heterostructures with quantum wells and impurity delta-layers in adjacent barriers are reviewed and analyzed. The positive magnetoresistance observed at low temperatures (Т < 20 K) and the dependence of the charge carrier mobility on the impurity concentration in the delta layers are related to the transport of carriers via two parallel channels with different mobilities, which are the channels formed by the structural and delta-layer quantum wells. The non-linear dependence of the current on the applied electric field strength is explained by the field-induced redistribution of charge carriers between these channels. | |
Keywords: | heterostructures, quantum wells, lateral conduction, magnetoresistance, delta
doping
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Edition: | Ukrainian Journal of Physics | | | 2014,
5,English |
007 Real-space transfer and non-linear lateral electric transport of electrons in heterostructures n- AlGaAs/GaAs with delta-layers of impurity in barriers |
Authors: | V.V. Vainberg, V.A.Kochelap,V.V.Koroteev,A.S. Pykyochuk, V.N. Poroshin, O.G. Sarbey | |
Summary: | Investigations of electron transport in specially developed AlGaAs/GaAs heterostructures have carried out. The heterostructures consist of quantum wells and delta-doped barriers with high concentration of shallow impurity. In such barriers due to overlap of the electron wave functions localized in the region of the δ-layers the conducting channels (impurity wells) are formed. It is shown that redistribution of electrons between the structural and impurity wells initiated by the applied lateral (in the plane of wells) electric field causes strong non-linearity in the structure conduction. The non-linearity appears at the field strength which is considerably less as compared to other known kinds of structures with the real-space transfer of hot charge carriers (the structures with uniformly doped barriers, with coupled wells one of which is δ-doped etc.) | |
Keywords: | heterostructures, quantum wells, lateral conduction, magnetoresistance, delta doping
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Edition: | In the book “Nanodimensional systems and nanomaterials: current state and perspectives of development of investigations in Ukraine”. “Academperiodika” Publishers of Nat. Acad. Sci. of Ukraine. | | | 2014,
5,Russian |
007 Theory of high-field electron transport in the heterostructures AlxGa1–xAs/GaAs/AlxGa1–xAs with delta-doped barriers. Effect of real-space transfer |
Authors: | V.V. Korotyeyev | |
Summary: | Steady-state electric characteristics of quantum heterostructures AlxGa1–xAs/GaAs/AlxGa1–xAs with -doped barriers have been analyzed in this work. It has been shown that at high doping the additional low-conductive channels are formed in the barrier layers. Current-voltage characteristics of the structure were obtained in the wide interval of applied electric fields up to several kV/cm being based on the solution of Boltzmann transport equation. It has been found that in the electric fields higher than 1 kV/cm the effect of exchange of the carriers between the high-conductive channel of the GaAs quantum well and the channels in the AlGaAs barriers becomes essential. This effect gives rise to the appearance of the strongly nonlinear current-voltage characteristics with a portion of negative differential conductivity. The developed model of heterostructure is adequate to those recently fabricated and studied by Prof. Sarbey’s group. The obtained results explain some observation of this paper. It has been found that the effect of electron real-space transfer takes place at both low temperatures and room temperatures, which opens perspectives to design novel type nanostructured current controlled devices. | |
Keywords: | quantum heterostructures, real-space transfer, electron transport | |
Edition: | Semiconductor Physics, Quantum Electronics & Optoelectronics | | | 2014,
11,English |
The events in the framework of the project |
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007 Executant:Institute of Physics, Department of Physics and Astronomy, Section Physical, Engineering and Mathematics 1. Physics of nanostructures Purpose:investigation of the ultra-high frequency properties of the semiconductor nanostructures with the real-space transfer of hot carriers and effects that provide appearance of the negative differential conduction (NDC), amplification and generation of the electromagnetic radiation of the sub-millimeter range. Expected results:Other (to increase production, improve working conditions, environmental improvement, energy savings, material savings, reduced equipment wear, increase productivity, improve efficiency of diagnosis and treatment, etc.) Stage 1:Development of theory of the real-space charge transfer in the system od quantum wells with selective doping in barriers. Development and testing of the electric and optical techniques for investigation of the real-space transfer of hot carriers, characterization of samples. Stage 2:Characterization of structures by the electric and optical methods, measurement of the band-to-band photoluminescence, in particular under strong electric field which initiates real0space transfer. Thepretical support of experiment. Stage 3:Theoretical and experimental investigation of the current-voltage characteristics of the structures with quantum wells and barriers doped by the deepimpurities. Stage 4:Investigation of the lateral electron transport ubder strong electric fields. Investigation of the Hall effect, magneto oscillating phenomena in the coupled wells and investigation of sub-millimeter emission. Stage 5:Determination of the negative differential conduction, measurement of amplification of the sub-millimeter emission. Calculations of the optimal characteristics of the resonator. Fabrication of the resonator and carrying out experiments on generation. The final report on project.
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