共查询到12条相似文献,搜索用时 0 毫秒
1.
Y. Qu S. L. Ban 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(3):321-329
Based on the dielectric continuum phonon model, uniaxialmodel and force balance equation the mobility of two dimensional electrongas in wurtzite AlxGa1-xN/GaN/AlxGa1-xN quantum wells isdiscussed theoretically within the temperature range dominated by opticalphonons. The dependences of the electron mobility on temperature, Al molarfraction and electron sheet density are presented including hydrostaticpressure effect. The built-in electric field is also taken into account. Itis found that under normal pressure the main contribution to the mobility isfrom the scattering of interface optical phonons in narrow (for well widthd < 12 Å) and wide (for d > 117 Å and d > 65 Å for finitelythick barriers and infinitely thick ones, respectively) wells, whereas thatis from the scattering of confined optical phonons in a well with anintermediate width. It is shown that the electron mobility decreases withincreasing Al molar fraction and temperature, whereas increases obviouslywith increasing electron sheet density. The theoretical calculated electronmobility is 978 cm2/V?s which is higher than an available experimentaldata 875 cm2/V?s when x equals to 0.58 at room temperature. Theresults under hydrostatic pressure considering the modification of strainindicate that the mobility increases slightly as hydrostatic pressureincreases from 0 to 10 GPa. 相似文献
2.
J.-J. Shi B.C. Sanders S.-H. Pan 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(1):113-119
We calculate the electron-phonon scattering rate for an asymmetric double barrier resonant tunneling structure based on dielectric
continuum theory, including all phonon modes, and show that interface phonons contribute much more to the scattering rate
than do bulk-like LO phonons for incident energies which are approximately within an order of magnitude of the Fermi energy.
The maximum scattering rate occurs for incident electron energies near the quantum well resonance. Subband nonparabolicity
has a significant influence on electron-phonon scattering in these structures. We show that the relaxation time is comparable
to the dwell time of electrons in the quantum well for a typical resonant tunneling structure.
Received: 23 December 1997 / Revised: 24 March 1998 / Accepted: 9 March 1998 相似文献
3.
B.H. Wu J.C. Cao G.Q. Xia H.C. Liu 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(1):9-14
A detailed calculation of interface phonon assisted electron intersubband transition in double GaAs/AlGaAs quantum well structure
is presented. Our calculation concentrates on the lowest two subbands which can be designed to be in resonance with a given
interface phonon mode. Various phonon mode profiles display quasi-symmetric or quasi-antisymmetric shapes. The quasi-antisymmetric
phonon modes give rise to much larger transition rates than those assisted by quasi-symmetric ones. The transition rate reaches
a maximum when the subband separation coincides with a given phonon mode energy. The calculation procedure presented here
can be easily applied to the design and simulation of other low dimensional semiconductor structures, such as quantum cascade
lasers.
Received 22 December 2002 Published online 23 May 2003
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ID="a"e-mail: bhwu@263.net 相似文献
4.
L. Silvestri F. Bassani G. Czajkowski B. Davoudi 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(1):89-102
We show how to compute nonlinear optical absorption spectra of an Asymmetric Double Quantum Well (ADQW) in the region of intersubband
electronic transitions. The method uses the microscopic calculation of the dephasing due to electron-electron and electron-phonon
scattering rates and the macroscopic real density matrix approach to compute the electromagnetic fields and susceptibilities.
The polarization dephasing and the corrections to the Rabi frequencies due to the electron-electron interaction are also taken
into account. For a proper choice of the QW widths and of the driving fields we obtain electromagnetically induced transparency.
This transparency has a very narrow linewidth when a single driving field is applied resonant to the transition between the
second and the third subband. In the case of two resonant driving fields or of a driving field resonant between the first
and third subband we obtain a large transparency enhancement over the entire absorption spectrum. Results are given for GaAs/GaAlAs
QWs and experiments are proposed.
Received 21 June 2001 and Received in final form 21 January 2002 相似文献
5.
E. Kogan M. Auslender M. Kaveh 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(3):373-376
Localization and dephasing of conduction electrons in a low carrier density ferromagnet due to scattering on magnetic fluctuations
is considered. We claim the existence of the “mobility edge”, which separates the states with fast diffusion and the states
with slow diffusion; the latter is determined by the dephasing time. When the “mobility edge” crosses the Fermi energy a large
and sharp change of conductivity is observed. The theory provides an explanation for the observed temperature dependence of
conductivity in ferromagnetic semiconductors and manganite pyrochlores.
Received 17 January 1999 and Received in final form 12 March 1999 相似文献
6.
A. Perali M. Sindel G. Kotliar 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,24(4):487-503
A number of normal state transport properties of cuprate superconductors are analyzed in detail using the Boltzmann equation.
The momentum dependence of the electronic structure and the strong momentum anisotropy of the electronic scattering are included
in a phenomenological way via a multi-patch model. The Brillouin zone and the Fermi surface are divided in regions where scattering between the electrons
is strong and the Fermi velocity is low (hot patches) and in regions where the scattering is weak and the Fermi velocity is
large (cold patches). We present several motivations for this phenomenology starting from various microscopic approaches.
A solution of the Boltzmann equation in the case of N patches is obtained and an expression for the distribution function away from equilibrium is given. Within this framework,
and limiting our analysis to the two patches case, the temperature dependence of resistivity, thermoelectric power, Hall angle,
magnetoresistance and thermal Hall conductivity are studied in a systematic way analyzing the role of the patch geometry and
the temperature dependence of the scattering rates. In the case of Bi-based cuprates, using ARPES data for the electronic
structure, and assuming an inter-patch scattering between hot and cold states with a linear temperature dependence, a reasonable
agreement with the available experiments is obtained.
Received 3 August 2001 and Received in final form 1st November 2001 相似文献
7.
S. Saib N. Bouarissa P. Rodríguez-Hernández A. Muñoz 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,60(4):435-438
We present a theoretical study of the structural properties, namely
lattice constant, bulk modulus and its pressure derivative of zinc-blende
GaxIn1-xN. The calculations are performed using first-principles
calculations in the framework of the density-functional-theory
within the local density approximation under the virtual
crystal approximation. The computed values are in good
agreement with the available experimental data. The composition dependence
of the studied quantities is examined. Besides, the deviation of the alloy
lattice constant from Vegard's law is evaluated. 相似文献
8.
V.Yu. Irkhin M.I. Katsnelson 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(4):481-486
Peculiarities of transport properties of three- and two-dimensional half-metallic ferromagnets are investigated, which are
connected with the absence of spin-flip scattering processes. The temperature and magnetic field dependences of resistivity
in various regimes are calculated. The resistivity is proportional to T
9/2 for T < T
* and to T
7/2 for T > T
*, T* being the crossover temperature for longitudinal scattering processes. The latter scale plays also an important role in magnetoresistance.
The contribution of non-quasiparticle (incoherent) states to the transport properties is discussed. It is shown that they
can dominate in the temperature dependence of the impurity-induced resistivity and in the tunnel junction conductivity.
Received 16 September 2002 / Received in final form 6 November 2002 Published online 31 December 2002 相似文献
9.
Spacer layer thickness fluctuation scattering in a modulation-doped Al<sub>x</sub>Ga<sub>1-x</sub>As/GaAs/Al<sub>x</sub>Ga<sub>1-x</sub>As quantum well
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We theoretically study the influence of spacer layer thickness fluctuation(SLTF) on the mobility of a twodimensional electron gas(2DEG) in the modulation-doped Al x Ga 1 x As/GaAs/Al x Ga 1 x As quantum well.The dependence of the mobility limited by SLTF scattering on spacer layer thickness and donor density are obtained.The results show that SLTF scattering is an important scattering mechanism for the quantum well structure with a thick well layer. 相似文献
10.
D. Varshney G. Joshi 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(4):523-534
The present paper addresses the high-pressure phase transformation and
mechanical properties of Ga1-xInxAs (x = 0.25, 0.5 and 0.75) by
formulating an effective interionic interaction potential. This potential
consists of the long-range Coulomb and charge transfer caused by the
deformation of the electron shells of the overlapping ions and the
Hafemeister and Flygare type short-range overlap repulsion extended upto the
second neighbor ions and the van der Waals (vdW) interaction. The estimated
values of phase transition pressure and the vast volume discontinuity in
pressure-volume (PV) phase diagram indicate the structural phase transition
from zinc blende (B3) to rock salt (B1). The equation of state curves plotted
between V (P)/ V (0) and pressure are for both the zincblende (B3) and rocksalt
(B1) structures. Further, the variations of the second and third order
elastic constants with pressure have followed a systematic trend, which are
almost identical to those exhibited by the observed data measured for other
compounds of this family. 相似文献
11.
12.
A. B. Dubois 《Russian Physics Journal》2008,51(1):51-58
In this work, the results of studying the electron-electron relaxation processes in a highly degenerate 2D-electron system
with a fine structure of energy spectrum and spatial distribution of electron density are reported. The relations for the
intra-and intersubband electron-electron interaction times are found and the matrix elements of a total screening potential
and a dielectric function are determined in the approximation far from the long-wave limit for a heavily doped heterojunction,
where two subbands of dimensional quantization are filled. It is shown that oscillations of the temperature and concentration
dependences of the electron-electron interaction time are due to excitation of plasma oscillations of the 2D-electron system
components.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 45–51, January, 2008. 相似文献