Conductance fluctuations and quantum chaotic scattering in semiconductor microstructures

We review recent experiments on aperiodic conductance fluctuations in ballistic GaAs/AlGaAs microstructures in the shape of a stadium billiard and a circle with point-contact leads, measured at millikelvin temperatures. Much of the observed behavior can be analyzed within a semiclassical approach to quantum chaotic scattering. After a brief review of the Landauer-Buttiker formulation of coherent transport, a variety of novel experimental phenomena and comparisons to semiclassical theory are presented. In particular, we discuss quantum-enhanced backscattering, the power spectrum of conductance fluctuations, crossover to the high-magnetic-field and tunneling regimes, and an application allowing the rate of phase-randomizing scattering to be measured in chaotic ballistic microstructures.     

Perspectives in electron scattering by microstructures

Summary In this paper the physical mechanisms of electron scattering in solids are studied, emphasis being placed on the processes relevant in electron spectroscopy and lithography. The essential features of the Monte Carlo approach to electron penetration are reviewed. Lithography applications are briefly discussed. In honour of Prof. Fausto Fumi on the occasion of his retirement from teaching.     

Brillouin scattering in microstructures involving GaAs

Light interaction with Rayleigh Surface Waves propagating parallel to the surface of GaAs substrates implanted with heavy ions has been used for the determination of the acoustic velocity in amorphous GaAs. A complete analysis of the peak-width of the scattered light from folded acoustic modes, including the contribution of the phonon lifetime and the light absorption, is presented for superlattices. In the case of the GaAs-AlAs systems, this analysis can explain the sharpness of the observed peaks.     

Electron-polariton scattering in semiconductor microcavities

In semiconductor microcavities, electron-polariton scattering has been proposed as an efficient process that can drive polaritons from the bottleneck region to the ground state, achieving Bose amplification of the optical emission. We present clear experimental observation of this process in a structure that allows control of the electron density and we report substantial enhancement of photoluminescence. We show that this enhancement is more effective at higher temperatures due to the different way that electron scattering processes either broaden or relax polaritons.     

Solitons in semiconductor microstructures with a two-dimensional electron gas

Nonlinear waves in a two-dimensional electronic plasma with metal screening gates are investigated. It is shown that solitons described by the KdV equation exist in such a system. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 7, 479–481 (10 October 1999)     

Resonant rayleigh scattering in semiconductor structures

Il Nuovo Cimento D - A detailed study of the relative role played by localized and/or propagating intermediate excitonic states in, resonant Rayleigh scattering (RRS) is presented for a large set...     

量子微结构中的Josephson 效应

文章为纪念Josephson 效应发现50周年而作.文章介绍了当前关于几种量子微结构中Josephson 效应的理论研究,涉及Josephson 效应的基本物理现象和它在某些热点材料中的独特表现,如单层石墨纳米条带中的0-π转变,二维拓扑绝缘体中的手征性边态超导电流,以及半导体微腔中激子极化激元凝聚体之间的Josephson 效应和直流-交流Josephson 电流的转变.     

Electron-phonon scattering in asymmetric semiconductor quantum-well structures

We calculate scattering rates of intrasubband and intersubband electronic transitions in asymmetric single quantum wells (QW's) and step QW's due to interface phonons, confined bulk-like LO phonons, and half-space LO phonons. The relative importance of the different phonon modes is analyzed. The results show that the electron-phonon scattering rates have intimate relation to the QW parameters.     

Dipole electron scattering in compensated semiconductor quantum wells

This paper reports on a theoretical study of conduction electron scattering by a system of dipoles formed by closely spaced positively and negatively charged centers in a quantum well.     

Stimulated Brillouin scattering in magnetized diffusive semiconductor plasmas

Using the hydrodynamical model and following the coupled mode approach, detailed analytical investigation of stimulated Brillouin scattering is performed in an electrostrictive semiconductor. The total induced current density including diffusion current density and the effective Brillouin susceptibility are obtained under off-resonant laser irradiation. The analysis deals with the qualitative behaviour of the Brillouin gain and transmitted intensity with respect to excess doping concentration and magnetic field. Efforts are directed towards optimizing the doping level and magnetic field to achieve maximum Brillouin gain at pump intensities far below the optical damage threshold level. It is found that by immersing a moderately doped semiconductor in a sufficiently strong magnetic field in transverse direction, one can achieve resonant enhancement of Brillouin gain provided the generated acoustic mode lies in the dispersionless regime.     

Resonant-Raman scattering from quasi-localized excitons in semiconductor quantum wells

Large polarization-dependent resonance enhancement is observed in first and second order Raman scattering in multiple quantum well $\text{GaAs}\text{(Al}{}_{\mathrm{x}}\text{Ga}{}_{\mathrm{1-x}}\text{)As}$ and $\text{GaAs}\text{AlAs}$ semiconductor heterostructures. Resonance enhancement is much stronger in the forbidden polarization than in the allowed and shows double resonance behaviour at incoming and outgoing photon energies. The resonance is stronger at incoming photon energies for one-phonon scattering and at outgoing photon energies for two-phonon scattering.     

Coherent control of polariton parametric scattering in semiconductor microcavities

In a pump-probe experiment, we have been able to control, with phase-locked probe pulses, the ultrafast nonlinear optical emission of a semiconductor microcavity, arising from polariton parametric amplification. This evidences the coherence of the polariton population near k=0, even for delays much longer than the pulse width. The control of a large population at k=0 is possible although the probe pulses are much weaker than the large polarization they control. With rising pump power the dynamics of the scattering get faster. Just above threshold the parametric scattering process shows unexpected long coherence times, whereas when pump power is risen the contrast decays due to a significant pump reservoir depletion. The weak pulses at normal incidence control the whole angular emission pattern of the microcavity.     

Toward classifying elementary microstructures in thin films by their scattering responses

The coupled dipole method (CDM) and the method of moments (MOM) can both be applied to study the light scattering responses of microstructures commnly found in optical and infrared thin films. A comparative analysis of the MOM and the CDM for these scattering problems is done. Three estimates of the polarizability scalars of subregional volumes are also compared.