In this paper we present a study of an exciton system where electrons and holes are confined in double quantum well structures. The dominating interaction between excitons such systems is dipole-dipole repulsion. We show that the tail leads to strong correlation substantially affects behavior system. Making use qualitative arguments estimates develop picture exciton-exciton correlations whole region temperature concentration exist. It appears at low degeneracy accompanied with multiparticle...

A gas of interacting excitons in quantum wells is studied. We obtain the Hamiltonian this by projection electron-hole plasma to exciton states and an expansion a small density. Matrix elements are rather sensitive geometry heterostructure. The mean field approximation gives blueshift spin splitting luminescence lines. also write down Boltzmann equation for estimate energy relaxation time resulting from exciton-exciton scattering. Making use these calculations, we succeeded explaining some...

Calculations of the hole mobility in a strained SiGe quantum well on (001) Si are carried out for case narrow which subband splittings large due to quantum-size effects. An envelope-function model valence-band structure and wave functions an infinite square calculations scattering rates single parabolic band with isotropic effective mass used delineate limitations imposed by lattice scattering, background impurities, alloy interface roughness. Additional mechanisms associated compositional...

We present an InAs-GaSb--based system in which the electric-field tunability of its 2D energy gap implies a transition towards thermodynamically stable excitonic condensed phase. Detailed calculations show 3 meV BCS-like appearing second-order phase with electric field. find this to be very sharp, solely due exchange interaction, and, so, exciton binding is greatly renormalized even at small condensate densities. This density gradually increases external field, thus enabling direct probe...

Mutual drag of two-dimensional (2D) and 3D electron gases in GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As/GaAs heterostructures is considered. The main purpose the paper to explain recent experiment Solomon et al. [Phys. Rev. Lett. 63, 2508 (1989)] which a current channel induced gate latter changed its sign when temperature decreased. It shown that Coulomb mutual scattering gives rise two mechanisms induction. first them direct momentum transfer...

A novel semiconductor switching device is proposed. It based on unique control over the two-dimensional band structure of an AlSb-GaSb-InAs-AlSb heterostructure. By applying small electric fields, virtually any value can be achieved for such parameters as energy gaps, effective masses, and carrier types densities in material. The proposed heterostructure readily fabricated with existing epitaxial techniques.

We propose a novel method to control the frequency of semiconductor lasers. The new technique allows fabricating three-terminal lasers with fast tuning and possibility implement intrinsically linearization laser sweep. electrical contact located between lower undoped cladding waveguide together upper enable pumping for optical gain. A voltage applied same under induces space charge limited current (SCLC) across cladding. Electrons driven into this layer create charge. affects refractive...

The theory of the uniform electric-field distribution instability in superlattices is developed. with respect to high-field domain formation was discovered some time ago by Esaki and Chang but no microscopic has been proposed so far. To determine condition we consider first conductivity a superlattice for arbitrary relations between width miniband, electric potential drop per period, energy uncertainty due scattering. Such general case can be described quantitatively help density matrix if...

Abstract The electronic properties of unstrained unrelaxed InAs x Sb 1− alloys have been determined in a wide range alloy compositions using IR magnetospectroscopy, magnetotransport and photoluminescence. All studied n-type background doping with electron concentration decreasing the content. composition dependence follows an empirical exponential law compositions. Both bandgap effective mass on exhibit negative bowing reaching lowest values at = 0.63: E g 0.10 eV, m * 0.0082 0 4.2 K....

The general physical features and a mathematical description of spectral diffusion in glasses at low temperatures is considered. condition found for when can be treated as Markovian process. reason the Lorenzian form two-level system line shape For case not it described by distribution functional or characteristic functional. evaluation reduced to solving differential equation second order an integral. theory applied two-pulse three-pulse echo decay. relationship between theoretical results...

Using numerical simulations we study the long-time relaxation of hopping conductivity. Even though no modern computation is able to simulate behavior a large size system over minutes or hours so as observe relaxation, have been show that and aging effect observed in experiments can be explained terms slow transitions between different pseudo ground states. This was achieved by showing pseudoground states may conductivities dispersion agreement with experimental data. We considered two...

Quasiparticles with Dirac-type dispersion can be observed in nearly gapless bulk semiconductors alloys which the bandgap is controlled through material composition. We demonstrate that Dirac realized short-period InAs1–xSbx/InAs1–ySby metamorphic superlattices tuned to zero by adjusting superlattice period and layer strain. The new has anisotropic carrier dispersion: energy associated in-plane motion proportional wave vector characterized Fermi velocity vF, corresponding growth direction...

We calculate here the energy spectrum of InAs/GaSb heterostructure taking into account a complicated, anisotropic, and nonparabolic structure valence band GaSb. In heterostructures GaSb layer overlaps with conduction InAs layer. The electrons in are coupled to holes hybridization gap is formed. coupling considered as small perturbation for problem two decoupled infinite quantum wells, one electrons. system shows features that result from anisotropy, dependence on in-plane vector, lifting...

We present the phase diagram of exciton gas in single and coupled quantum wells. In latter case, electrons holes are spatially separated. both wells there is a Mott transition from to electron-hole plasma. temperatures below well, crossover biexciton phase. The formation rules out Kosterlitz-Thouless excitons. wells, strong direct repulsion between excitons prevents formation. If separation large enough, decrease temperature leads ferromagnetic with spontaneous spin polarization. Further...

A simple model of a series circuits comprising nonlinear resistor and capacitor in parallel is suggested for description I-V-characteristic instabilities the formation high-field domains superlattices. The justified if subbands superlattice are destroyed by high field or scattering transport sequential tunneling. In case wide second subband, breaks down two parts. first, tunneling, but part, electrons propagate subband there. Simple physical arguments show that I-V characteristics such has...

In this paper a remote phonon scattering of channel electrons in field-effect transistor (FET) with high dielectric constant (κ) insulator between the gate and is studied theoretically. The spectrum phonons confined κ layer its modification by screening investigated. Only two modes five participate electron-phonon scattering. suppresses one but increases other. Numerical results for mobility limited only were obtained Si FET HfO2 SiO2 metallic gate. A surprising result reduction compared to...

We study the correlations of two-dimensional dipolar bosons with excitons in semiconductor bilayers as a specific case, whole temperature-concentration region. show that at low concentrations, Bose degeneracy is accompanied by strong multi-particle and system behaves liquid. At high concentrations repulsion suppresses quantum coherence classical liquid down to temperature lower than typical for gas. The interaction energy particles sensitive tool measurement correlations. This theory can...

We studied theoretically excitons in narrow-coupled InAs/GaSb quantum wells where there is not any overlap between the InAs conduction subband and GaSb valence subband. In this case, do exist equilibrium luminescence of pumped can be observed. calculated exciton binding energy making use variational method. The resulting around 4 meV. also lifetime for both radiative recombination nonradiative recombination. Due to unique band alignment InAs/GaSb, happen via two channels: first, mixing with...

We study the mobility of a two-dimensional electron gas (2DEG) which forms at an inverted GaAs/AlAs interface, in structure where back gate and front are both used to modify density 2DEG. The availability two different control voltages provides special opportunity gain insight into scattering mechanisms. find that we can induce significant change mobility, fixed density, by changing interface roughness scattering, depends on perpendicular electric field acting also changes for current...

We reconsider the classical problem of quantum-mechanical resistance due to a reflection off heterostructure interface. In presence current, electron distribution in vicinity interface is different from that bulk angular dependence coefficient. The also modifies concentration, leading violation local neutrality. This creates self-consistent electric field and affects distribution. depends on actual form Incorporating all these factors kinetic transport model, we have reduced evaluation an...

In this paper a detailed derivation of the boundary conditions for envelope functions is carried out making use k\ensuremath{\cdot}p method. The resulting are different from those Harrison by an extra term originating surface energy. This removes difference between expressions transmission coefficient obtained with help microscopical calculations and envelope-function case simple band structure contain two independent parameters. It shown that general suggested Ando Mori which has to be...

In plane and growth direction electron effective mass in short period InAs/GaSb semiconductor superlattices (SL) was measured using cyclotron resonance at different orientations of magnetic field with respect to SL direction. It demonstrated that the spectrum near bottom subband has 3D character, in-plane masses ranging from 0.023 m0 0.028 0.03–0.034 depending on conditions. The are close those calculated weak coupling limit Kronig-Penney model. this is a weighted average corresponding bulk...