-
[show abstract]
[hide abstract]
ABSTRACT: Results of numerical simulation of the weak localization in two-dimensional systems in wide range of magnetic filed are presented. Three cases are analyzed: (i) the isotropic scattering and randomly distributed scatterers; (ii) the anisotropic scattering and randomly distributed scatterers; (iii) the isotropic scattering and the correlated distribution of the scatterers. It is shown that the behavior of the conductivity beyond the diffusion regime strongly depends on the scattering anisotropy and correlation in the scatterer distribution.
04/2006;
-
[show abstract]
[hide abstract]
ABSTRACT: The results of an experimental study of interaction quantum correction to the conductivity of two-dimensional electron gas in A$_3$B$_5$ semiconductor quantum well heterostructures are presented for a wide range of $T\tau$-parameter ($T\tau\simeq 0.03-0.8$), where $\tau$ is the transport relaxation time. A comprehensive analysis of the magnetic field and temperature dependences of the resistivity and the conductivity tensor components allows us to separate the ballistic and diffusion parts of the correction. It is shown that the ballistic part renormalizes in the main the electron mobility, whereas the diffusion part contributes to the diagonal and does not to the off-diagonal component of the conductivity tensor. We have experimentally found the values of the Fermi-liquid parameters describing the electron-electron contribution to the transport coefficients, which are found in a good agreement with the theoretical results.
01/2006;
-
[show abstract]
[hide abstract]
ABSTRACT: The interaction correction to the conductivity of 2D hole gas in strained GaAs∕InxGa1−xAs∕GaAs quantum well structures was studied. It is shown that the Zeeman splitting, spin relaxation, and ballistic contribution should be taken into account for reliable determination of the Fermi-liquid constant F0σ. The proper consideration of these effects allows us to describe both the temperature and magnetic field dependences of the conductivity and to find the value of F0σ.
Phys. Rev. B. 10/2005; 72(16).
-
[show abstract]
[hide abstract]
ABSTRACT: The interaction correction to the conductivity of 2D hole gas in strained GaAs/In$_x$Ga$_{1-x}$As/GaAs quantum well structures was studied. It is shown that the Zeeman splitting, spin relaxation and ballistic contribution should be taking into account for reliable determination of the Fermi-liquid constant $F_0^\sigma$. The proper consideration of these effects allows us to describe both th temperature and magnetic field dependences of the conductivity and find the value of $F_0^\sigma$.
04/2005;
-
[show abstract]
[hide abstract]
ABSTRACT: Low-field magnetoresistance in p-type strained quantum wells is studied. It is shown that the Rashba mechanism leads to the cubic in quasimomentum spin-orbit splitting of the hole energy spectrum and the antilocalization behavior of low-field magnetoresistance is well described by the Hikami-Larkin-Nagaoka expression.
10/2004;
-
[show abstract]
[hide abstract]
ABSTRACT: We have studied the temperature dependence of the Hall effects in multilayer selectively doped InGaAs/GaAs heterostructures
with quantum dots (QDs). It was found that structures possessing photoconductivity in the IR range exhibit a sharp (nearly
exponential) growth of the conductivity and Hall mobility in the temperature interval from 8 to 30 K at a virtually constant
Hall coefficient and electron density. A new mechanism of the lateral photoconductivity in the structures with QDs is proposed
which is related to the change in the electron mobility in the two-dimensional channel as a result of a decrease in the Coulomb
scattering on charged QDs.
Technical Physics Letters 01/2004; 30(9):795-798. · 0.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We show that the study of conductivity nonlinearity gives a possibility to determine the condition when the diffusion conductivity changes to the hopping one with increasing disorder. It is experimentally shown that the conductivity of single quantum well GaAs/InGaAs/GaAs heterostructures behaves like diffusive one down to value of order $10^{-2}e^2/h$.
01/2004;
-
Bulletin of the Russian Academy of Sciences Physics 01/2004; 68(1):63.
-
[show abstract]
[hide abstract]
ABSTRACT: Low-field magnetoconductivity caused by the quantum interference is studied in the gated 2D quantum well structures with the composition gradient. It is shown that the Dresselhaus mechanism well describes an antilocalization minimum on the conductivity-magnetic field curve.
12/2003;
-
[show abstract]
[hide abstract]
ABSTRACT: Weak antilocalization is studied in an InGaAs quantum well. Anomalous magnetoresistance is measured and described theoretically in fields perpendicular, tilted and parallel to the quantum well plane. Spin and phase relaxation times are found as functions of temperature and parallel field. It is demonstrated that spin dephasing is due to the Dresselhaus spin-orbit interaction. The values of electron spin splittings and spin relaxation times are found in the wide range of 2D density. Application of in-plane field is shown to destroy weak antilocalization due to competition of Zeeman and microroughness effects. Their relative contributions are separated, and the values of the in-plane electron g-factor and characteristic size of interface imperfections are found. Comment: 8 pages, 8 figures
12/2003;
-
[show abstract]
[hide abstract]
ABSTRACT: The interference induced transverse negative magnetoresistance of GaAs/InGaAs/GaAs quantum well heterostructures has been studied in the presence of strong in-plane magnetic field. It is shown that effect of in-plane magnetic field is determined by the interface roughness and strongly depends on the relationship between mean free path, phase breaking length and roughness correlation length. Analysis of the experimental results allows us to estimate parameters of short- and long-range correlated roughness which have been found in a good agreement with atomic force microscopy data obtained for just the same samples. Comment: 16 pages, 8 figures, REVTeX 4
11/2003;
-
[show abstract]
[hide abstract]
ABSTRACT: Dependences of electrical conductivity σ on temperature and electric-field strength were studied in a wide range of conductivities
(from σ ≪ e
2/ℏ to σ ≫ e
2/ℏ) in GaAs/InGaAs/GaAs structures with a two-dimensional electron gas. It is shown that one cannot reliably determine the
mechanism of conductivity from the temperature dependence of ohmic conductivity. Studies of nonohmic conductivity make it
possible to determine the range of values of low-temperature conductivity that correspond to the transition from the diffusion
mechanism of conductivity to the hopping mechanism. It is shown that, in the structures under investigation, the conductivity
is still controlled by diffusion as the degree of disorder increases even when the low-temperature conductivity is much lower
than e
2/ℏ.
Semiconductors 01/2003; 37(6):705-709. · 0.63 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The contribution of the electron-electron interaction to conductivity is analyzed step by step in gated GaAs/InGaAs/GaAs heterostructures with different starting disorder. We demonstrate that the diffusion theory works down to $k_F l\simeq 1.5-2$, where $k_F$ is the Fermi quasimomentum, $l$ is the mean free paths. It is shown that the e-e interaction gives smaller contribution to the conductivity than the interference independent of the starting disorder and its role rapidly decreases with $k_Fl$ decrease.
10/2002;
-
[show abstract]
[hide abstract]
ABSTRACT: Results of detailed investigations of the conductivity and Hall effect in gated single quantum well GaAs/InGaAs/GaAs heterostructures with two-dimensional electron gas are presented. A successive analysis of the data has shown that the conductivity is diffusive for $k_F l=25-2$ and behaves like diffusive one for $k_F l=2-0.5$ down to the temperature T=0.4 K. It has been therewith found that the quantum corrections are not small at low temperature when $k_F l\simeq 1$. They are close in magnitude to the Drude conductivity so that the conductivity $\sigma$ becomes significantly less than $e^{2}/h$ (the minimal $\sigma$ value achieved in our experiment is about $3\times 10^{-8}\Omega^{-1}$ at $k_Fl\simeq 0.5$ and $T=0.46$ K). We conclude that the temperature and magnetic field dependences of conductivity in whole $k_Fl$ range are due to changes of quantum corrections.
12/2001;
-
[show abstract]
[hide abstract]
ABSTRACT: The temperature and gate voltage dependences of the phase breaking time are studied experimentally in GaAs/InGaAs heterostructures with single quantum well. It is shown that appearance of states at the Fermi energy in the doped layers leads to a significant decrease of the phase breaking time of the carriers in quantum well and to saturation of the phase breaking time at low temperature. Comment: 4 pages, 6 figures
06/2001;
-
[show abstract]
[hide abstract]
ABSTRACT: The quantum correction to the conductivity have been studied in two types of 2D heterostructures: with doped quantum well and doped barriers. The consistent analysis shows that in the structures where electrons occupy the states in quantum well only, all the temperature and magnetic field dependencies of the components of resistivity tensor are well described by the theories of quantum corrections. The contribution of electron-electron interaction to the conductivity have been determined reliably in the structures with different electron density. A possible reason of large scatter in experimental data concerning the contribution of electron-electron interaction, obtained in previous papers, and the role of the carriers, occupied the states of the doped layers, is discussed. Comment: 10 pages with 9 figures
04/2001;
-
[show abstract]
[hide abstract]
ABSTRACT: We report experimental observations of a novel magnetoresistance (MR) behavior of two-dimensional electron systems in perpendicular magnetic field in the ballistic regime for kBTτ/ℏ>1. The MR grows with field and exhibits a maximum at fields B>1/μ where μ is the electron mobility. As temperature increases, the magnitude of the maximum grows and its position moves to higher fields. This effect is universal: it is observed in various Si- and GaAs-based two-dimensional electron systems. We compared our data with recent theory based on the Kohn anomaly modification in magnetic field and found qualitative similarities and discrepancies.
Phys. Rev. B. 79(20).
-
[show abstract]
[hide abstract]
ABSTRACT: The temperature and magnetic-field dependences of the conductivity of the heterostructures with asymmetric InxGa1−xAs quantum well are studied. It is shown that the metalliclike temperature dependence of the conductivity observed in the structures investigated is quantitatively understandable within the whole temperature range, T=0.4–20 K. It is caused by the interference quantum correction at fast spin relaxation for 0.4 K<T<1.5 K. At higher temperatures, 1.5 K<T<4 K, it is due to the interaction quantum correction. Finally, at T>4–6 K, the metalliclike behavior is determined by the phonon scattering.
Phys. Rev. B. 75(19).
-
[show abstract]
[hide abstract]
ABSTRACT: Quantum corrections to the conductivity have been studied in the two types of low-mobility two-dimensional heterostructures: those with doped quantum well, and doped barriers. The consistent analysis shows that for the structures where electrons occupy the states only in the quantum well, all the temperature and magnetic field dependences of the components of resistivity tensor are well described by the theories of the quantum corrections. Contribution of the electron-electron interaction to the conductivity has been reliably determined for the structures with different electron density. A possible reason of large scatter in experimental data relating to the contribution of electron-electron interaction, obtained in previous papers, is analyzed. The role of the carriers occupying the states of the doped layers is discussed.
Phys. Rev. B. 64(23).
-
[show abstract]
[hide abstract]
ABSTRACT: Results of experimental study of the weak localization in gated AlxGa1−xAs/GaAs/AlxGa1−xAs structures with artificial inhomogeneity of potential relief are presented. It has been found that the shape of the magnetoconductivity curve differs significantly from that measured for the homogeneous two-dimensional gas. This difference is shown to be caused by the difference in statistics of closed paths. The area distribution function of closed paths has been obtained using the Fourier transformation of the experimental magnetoconductivity curves taken at different temperatures. The results obtained are in qualitative agreement with the results of computer simulation.
Phys. Rev. B. 78(19).
