Precision of quantization of the hall conductivity in a finite-size sample: Power law

A microscopic calculation of the conductivity in the integer quantum Hall effect (IQHE) mode is carried out. The precision of quantization is analyzed for finite-size samples. The precision of quantization shows a power-law dependence on the sample size. A new scaling parameter describing this dependence is introduced. It is also demonstrated that the precision of quantization linearly depends on the ratio between the amplitude of the disorder potential and the cyclotron energy. The data obtained are compared with the results of magnetotransport measurements in mesoscopic samples.     

Temperature dependence of the effective coefficient of Auger recombination in 1.3 μm InAs/GaAs QD lasers

Semiconductor laser heterostructures containing five and ten sheets of InAs/GaAs QDs on GaAs substrates, with an emission wavelength of ～1.3 μm, have been studied. Dependences of the nonradiative lifetime and effective Auger coefficient in QDs are obtained from an analysis of temperature and current dependences of the efficiency of spontaneous radiative recombination. The zero-threshold Auger recombination channel in QDs is shown to dominate at low (below 200 K) temperature, whereas at higher temperatures the quasithreshold channel becomes dominant. The effective 3D Auger coefficient is estimated in the approximation of a spherical QD, and a good agreement with the experimental data is obtained.     

Comparative Analysis of the Electroluminescence Efficiency in Type-I and Type-II Heterostructures Based on III–V Narrow-Gap Compounds

Semiconductors - We study in detail the mechanisms of radiative and Auger recombination in type-I and type-II heterostructures based on III–V narrow-gap materials. The presence of a...     

Role of Acoustoelectric Interaction in the Formation of Nanoscale Periodic Structures of Adsorbed Atoms

The role of acoustoelectric effects in the formation of nanoscale structures of adatoms, resulting from the self-consistent interaction of adatoms with a surface acoustic wave and the electronic subsystem, is studied for the case of charged and uncharged adatoms. It is shown that an increase in the doping level of a semiconductor with donor impurities at a fixed average adatom concentration results in an increase in the critical temperature below which self-organization processes occur.     

Effect of intraband carrier relaxation on the threshold characteristics of quantum well lasers

The effect of intraband carrier relaxation on the threshold characteristics of InGaAsP quantum well (QW) lasers is studied. The dependence of the intraband hole-hole relaxation time τ _int on temperature and carrier density is analyzed. It is shown that taking into account the finiteness of τ _int and its dependence on temperature and carrier density strongly affects the gain and the threshold current density of QW lasers.     

Relationship between quasi-threshold and thresholdless auger recombination processes in InAs/GaAs quantum dots

The principal mechanisms of the nonradiative (Auger) recombination of nonequilibrium charge carriers in semiconductor heterostructures with quantum dots (QDs) are considered. It is shown that the Auger recombination process in QDs can proceed, in addition to a threshold mechanism, by means of two other substantially different mechanisms—thresholdless and quasi-threshold—and either of these can predominate, depending on the QD size. For a QD radius of ～30 Å, the probability of Auger recombination is comparable with that of radiative recombination.     

Effect of electron-electron and electron-hole collisions on intraband population inversion of electrons in stepped quantum wells

The effect of intersubband electron-electron (e-e) and electron-hole (e-h) scattering on intraband population inversion of electrons in a stepped InGaAs/AlGaAs quantum well is investigated. The characteristic times of the most probable e-e and e-h processes, which affect the electron densities on the excited levels, are calculated for the temperature range 80–300 K. Dependences of these times on the electron and hole density on the ground levels are studied. Temperature dependences of the intraband inversion of population for two nonequilibrium densities are calculated by solving a system of rate equations. It is shown that the intersubband e-e and e-h scattering only slightly affects the population inversion for electron densities below 1×10¹² cm^?2.     

The role of electron-electron interaction in the process of charge-carrier capture in deep quantum wells

The role of electron-electron interaction in the process of electron capture to a deep quantum well is investigated. Using two-level and three-level quantum wells as examples, the basic electron-capture mechanisms, i.e., the interaction with optical phonons and the Coulomb electron-electron interaction, are considered, and the corresponding capture probabilities and electron lifetimes are calculated. The effect of Auger recombination on the charge-carrier distribution in a quantum well is also taken into account. With this taken into consideration, a set of rate equations is solved for a nonsteady-state mode, and the time dependences of the electron concentration at the ground energy level in the quantum well are found. The contributions of each of the recombination processes under consideration are shown.     

The influence of gain saturation on the output power of quantum-well semiconductor lasers

The light-power characteristic of a quantum-well semiconductor laser is theoretically studied taking into account the gain saturation effect. It is shown that, at high drive current densities, this light-current characteristic becomes nonlinear. The results obtained are in a good agreement with the experimental data.     

Carrier Lifetime in Semiconductors with Band-Gap Widths Close to the Spin-Orbit Splitting Energies

Semiconductors - Expressions for the Auger- and radiative-recombination rates are derived in terms of Kane’s model for materials with a band-gap width close to the spin-orbit splitting...