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1.
R. Takayama N.H. Kwong I. Rumyantsev M. Kuwata-Gonokami R. Binder 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(4):445-462
A detailed numerical analysis of exciton-exciton interactions in semiconductor quantum wells is presented. The theory is based
on the dynamics-controlled truncation formalism and evaluated for the case of resonant excitation of 1s-heavy-hole excitons. It is formulated in terms of standard concepts of scattering theory, such as the forward-scattering
amplitude (or T-matrix). The numerical diagonalization of the exciton-exciton interaction matrix in the 1s-approximation yields the excitonic T-matrix. We discuss the role of the direct and exchange interaction in the effective two-exciton Hamiltonian, which determines
the T-matrix, evaluated within the 1s-subspace, and also analyze the effects of the excitonic wave function overlap matrix. Inclusion of the latter is shown to
effectively prevent the 1s-approximation from making the Hamiltonian non-hermitian, but a critical discussion shows that other artefacts may be avoided
by not including the overlap matrix. We also present a detailed analysis of the correspondence between the excitonic T-matrix in the 1s-approximation and the well-known T-matrix governing two-particle interactions in two dimensional systems via short-range potentials.
Received 3 August 2001 and Received in final form 26 December 2001 相似文献
2.
We reconsider the semiconductor trions from scratch. We first determine the very many “reasonable” ways to write the trions
in first quantization. We then select the forms which are easy to relate to physical pictures. In a second part, we derive
the corresponding creation operators in second quantization. We pay particular attention to the expression of the X- trion in terms of exciton and free-electron, as it is the one adapted to future works on many-body effects with trions.
Received 27 May 2002 / Received in final form 18 December 2002 Published online 20 June 2003
RID="a"
ID="a"e-mail: combescot@gps.jussieu.fr 相似文献
3.
O. Betbeder-Matibet M. Combescot 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(4):517-523
Pauli exclusion between the carriers of N excitons induces novel many-body effects, quite different from the ones generated by Coulomb interaction. Using our commutation
technique for interacting close-to-boson particles, we here calculate the Hamiltonian expectation value in the N-ground-state-exciton state. Coulomb interaction enters this quantity at first order only by construction; nevertheless, due
to Pauli exclusion, subtle many-body effects take place, which give rise to terms in (Na
x
3/)n with n ≥ 2. An exact procedure to get these density dependent terms is given.
Received 11 February 2002 / Received in final form 30 May 2002 Published online 6 March 2003
RID="a"
ID="a"e-mail: combescot@gps.jussieu.fr 相似文献
4.
J.J. Liu S.F. Zhang Y.X. Li X.J. Kong 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(1):17-20
Using a two-parameter wave function, we calculate variationally the binding energy of an exciton bound to an ionized donor
impurity (D+,X) in GaAs-AlxGa1-xAs quantum wells for the values of the well width from 10 to 300 ?, when the dopant is located in the center of the well and
at the edge of the well. The theoretical results confirm that the previous experimental speculation proposed by Reynolds et al. [Phys. Rev. B 40, 6210 (1989)] is the binding energy of D+,X for the dopant at the edge of the well. In addition, we also calculate the center-of-mass wave function of the exciton and
the average interparticle distances. The results are discussed in detail.
Received 17 July 2000 and Received in final form 13 November 2000 相似文献
5.
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
6.
Z. P. Wang X. X. Liang X. Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(1):41-46
Polaron effects on excitons in parabolic quantum wells are
studied theoretically by using a variational approach with the so-called
fractional dimension model. The numerical results for the exciton binding
energies and longitudinal-optical phonon contributions in
GaAs/Al0.3Ga0.7As parabolic quantum well structures are obtained as functions of the well width. It is shown that the exciton binding energies
are obviously reduced by the electron (hole)-phonon interaction and the polaron effects are un-negligible. The results demonstrate
that the fractional-dimension variational theory is effectual in the investigations of excitonic polaron problems in parabolic
quantum wells. 相似文献
7.
K.T. Stoychev M.T. Primatarowa K. Marinov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):301-304
Effects of the exciton and polariton dispersions and the nonlinear exciton and photon interactions on the properties of polariton
solitons in molecular crystals are investigated. Higher-order terms and phase-modulation (chirp) are taken into account. Bright-
and dark-soliton solutions of the resulting modified nonlinear Schr?dinger (NLS) equation are presented. Nonlinearity- and
dispersion-induced critical points on the polariton dispersion curve are obtained, separating regions with different solutions.
Received 2 October 2001 / Received in final form 23 May 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: Stoychev@issp.bas.bg 相似文献
8.
O.A. Yeshchenko M.M. Biliy Z.Z. Yanchuk 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(1):37-43
Excitonic absorption, reflection and photoluminescence spectra of mixed Zn(P1-xAsx)2 crystals over the full range of x ( 0 ?
x
? 1) and Zn1-xCdxP2 crystals at 0 ?
x
? 0.05 have been studied at low temperatures (1.8 K). The decrease of the energy gap in Zn(P1-xAsx)2 at the increase of x occurs slightly sublinearly. The rydbergs of excitonic series in this crystals decrease as well, and the dependences Ry
(
x
) for all series are strongly superlinear at small x. In Zn1-xCdxP2 crystals the energy gap and rydbergs decrease at the increase of x (at 0 ?
x
? 0.05) as well. The dependences of Eg and Ry on x are considerably stronger in Zn(P1-xAsx)2 than in Zn1-xCdxP2. At the increase of x the half-width of excitonic absorption lines increases monotonically in both type crystals that is evidence of the increasing
role of fluctuations of crystal potential.
Received 13 March 2002 Published online 9 July 2002 相似文献
9.
R. Schuster M. Knupfer D. R.T. Zahn H. Berger 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(1):25-28
We have investigated the polarization and momentum
dependence of singlet excitons in pentacene molecular crystals
using inelastic electron scattering. Our results demonstrate that
both the direction as well as the absolute value of the momentum
are decisive for the spectral intensity of these excitons.
Possible implications of this observation for a microscopic
understanding of excitons in organic molecular crystals are
discussed. 相似文献
10.
The negatively charged exciton in double-layer quantum dots 总被引:1,自引:0,他引:1
Wenfang Xie 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(3):385-389
The hyperangular equation for charged semiconductor complexes in a double-layer harmonic quantum dot was solved numerically
by using the correlated hyperspherical harmonics as basis functions. By using this method, we have calculated the energy spectra
of the low-lying states of a charged exciton as a function of the radius of the quantum dot and the binding energy spectra
of the ground state as a function of the radius of the quantum dot for a few values of the distance between the vertically
coupled dots and the electron-to-hole mass ratio.
Received 3 December 1999 相似文献
11.
J. Bellessa V. Voliotis T. Guillet D. Roditchev R. Grousson X.L. Wang M. Ogura 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(4):499-505
We report on time-resolved microphotoluminescence experiments in a single GaAs/GaAlAs V-shaped quantum wire as a function
of optical excitation intensity. At low pump power we observe that excitons are localized in quantum boxes formed by the local
potential minima existing along the wire axis. As the pump power is increased, state filling of the lowest lying levels of
the boxes appears. When two carriers occupy the first excited level of the box, a very efficient Auger scattering occurs,
leading to a transfer of carriers from one box to another neighbouring one. The intradot Auger scattering time has been measured
and is of the same order of magnitude as the LA-phonon emission rate.
Received 5 February 2001 相似文献
12.
M. Knupfer K. Widder M. Sing O. Knauff J. Fink 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,6(3):323-328
We have measured the dispersion of plasmon excitations in polycrystalline Sn, Pb, Cd and Zn using electron energy-loss spectroscopy
(EELS) in transmission. These metals show a remarkable deviation of their plasmon behaviour from standard theoretical expectations
which can be attributed to the presence of shallow core levels in the energetic neighborhood of the plasmon energy. The position
of the plasmon resonance in the long wavelength limit is in line with predictions from model assumptions taking into account
the core level polarization effects. We show that not only the plasmon energy in the optical limit but also the plasmon dispersion
is altered by the interaction of the charge carrier plasmon and the core level excitations.
Received: 15 June 1998 / Revised and Accepted: 9 July 1998 相似文献
13.
Y. Chen R. Cingolani J. Massies G. Neu F. Turco J. C. Garcia 《Il Nuovo Cimento D》1988,10(9):1093-1114
Summary Measurements of photoluminescence, excitation photoluminescence and reflectance are performed at various temperatures on a
series of GaAs/Ga1−x
Al
x
As quantum well structures grown by molecularbeam epitaxy. The selective photoluminescence data of the GaAs buffer layers
are analysed in order to correlate the optical properties with the growth conditions. The Stokes shift of the excitation emission
line from quantum wells is investigated under various excitation conditions. A considerable decrease of the Stokes shift is
observed in the case of nonresonant and intense excitations. Also the extrinsic photoluminescence, as well as its temperature
dependence, are interpreted. In addition, the temperature effects on both the bulk and quantum well spectra are shown to clarify
the excitation features and the contribution of the interband transitions.
To speed up publication, the authors of this paper has agreed to not receive the proofs for correction. 相似文献
14.
Applying the method of spectral interferometry we investigate the phase of reflected light at a ZnSe-ZnSxSe1−x heterostructure. We find a series of polariton modes propagating through the ZnSe layer. They can be related to the different polariton branches split of at the heavy- and light-hole excitons. The phase shows pronounced changes around these modes. The strongest changes by 2π appear at the modes of lowest order located weakly above the exciton resonances, while they are smaller for higher modes. Our experimental findings can be explained considering spatial dispersion, Pekar's additional boundary conditions and a weak extension of the excitonic polarization into the ZnSxSe1−x cladding layers. 相似文献
15.
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
RID="a"
ID="a"e-mail: bhwu@263.net 相似文献
16.
W. Ouerghui J. Martinez-Pastor J. Gomis M. A. Maaref D. Granados J. M. García 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(2):217-223
Exciton recombination dynamics in vertical stacks of InGaAs quantum rings have been studied by means of continuous wave and
time resolved
photoluminescence under low excitation density conditions. We have paid
special attention to the effect of the carrier coupling on the exciton
radiative lifetime: weak (14 nm spacer sample), intermediate (4.5 nm spacer
sample), where the size filtering effects (towards small rings) compensate
partially that arising from carrier coupling (towards lower energies), and
strong electron and hole coupling (1.5 nm spacer sample) between layers.
Experimental decay times in the latter two cases have been compared to the
times simulated with a multi-quantum well based model, which accounts for
the observed change of carrier coupling regime. The most important effect is
observed when the hole wave function overlap along the growth direction
becomes important (1.5 nm spacer sample). This situation makes important the
lateral tunneling of excitons between rings, given their large lateral size,
which is characterized by times around 5 ns at the emission peak energy
(rings with the most probable size of the distribution). 相似文献
17.
A. Benfredj D. Gamra S. Romdhane T. Barhoumi C. Guthmann J.L. Monge H. Bouchriha 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(3):385-391
The effect of a magnetic field (6 kG) on the delayed fluorescence in a 1,4-Dibromonaphtalene at 300 K and 20 K is analysed
using a new approach of calculation of the triplet-triplet annihilation rate constant. The agreement of the best fit between
experiment and theory allows reaching at 300 K and 20 K respectively the lifetimes and the interaction constant of the triplets
pairs.
Received 12 March 1999 and Received in final form 27 April 2000 相似文献
18.
S. Schulz S. Schumacher G. Czycholl 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(1):51-60
We present an sp
3 tight-binding model for the calculation of the electronic and optical properties of wurtzite semiconductor quantum dots (QDs).
The tight-binding model takes into account strain, piezoelectricity, spin-orbit coupling and crystal-field splitting. Excitonic
absorption spectra are calculated using the configuration interaction scheme. We study the electronic and optical properties
of InN/GaN QDs and their dependence on structural properties, crystal-field splitting, and spin-orbit coupling. 相似文献
19.
O.M. Schmitt D.B. Tran Thoai P. Gartner H. Haug 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(2):217-222
The dephasing and relaxation kinetics of bosonic excitons interacting with a thermal bath of acoustic phonons is studied after
coherent pulse excitation. The kinetics of the induced excitonic polarization is calculated within Markovian equations both
for subcritical and supercritical excitation with respect to a Bose-Einstein condensation (BEC). For excited densities n below the critical density , an exponential polarization decay is obtained, which is characterized by a dephasing rate . This dephasing rate due to phonon scattering shows a pronounced exciton-density dependence in the vicinity of the phase
transition. It is well described by the power law that can be understood by linearization of the equations around the equilibrium solution. Above the critical density we get
a non-exponential relaxation to the final condensate value p0 with that holds for all densities. Furthermore we include the full self-consistent Hartree-Fock-Bogoliubov (HFB) terms due to
the exciton-exciton interaction and the kinetics of the anomalous functions . The collision terms are analyzed and an approximation is used which is consistent with the existence of BEC. The inclusion
of the coherent exciton-exciton interaction does not change the dephasing laws. The anomalous function Fk exhibits a clear threshold behaviour at the critical density.
Received 13 December 1999 相似文献
20.
A. D'Andrea D. Schiumarini 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(1):87-101
The optical properties of Bragg quantum wells are studied
for exciton confinement under center-of-mass quantization. A variational
model of Wannier exciton envelope function, that embodies the correct
boundary conditions for center-of-mass, is adopted for calculation. The
present non-adiabatic exciton model is compared with adiabatic results and
with heuristic “hard sphere” model. The radiative self-energy of a
single-quantum well (SQW) and multi-quantum wells (MQWs) are computed in the
semiclassical framework, and in effective mass approximation, by
self-consistent solution of Schroedinger and Maxwell equations. This
microscopic solution is free from “fitting” parameter values, except for
the non-radiative broadening, and also the exciton dead-layer and the
additional boundary condition are not taken ad hoc, but come coherently
from the variational principle and self-consistent Schroedinger-Maxwell
solution. Dispersion curves of exciton-polariton propagating in a MQW, under
Bragg condition, are studied by selected numerical examples. The case of
optical gap in correspondence of higher excited states is studied, and,
moreover, the interesting effect of gap enhancement or inhibition, in
correspondence of non-resonant Bragg energy, will be addressed. 相似文献