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The statistics of photon correlations in the emission of single InAs/AlGaAs quantum dots grown by molecular beam epitaxy and fitted with AlGaAs waveguide nanoantennas for efficient extraction of radiation is investigated. A single-photon source for the red spectral range with an average emission rate exceeding 5 MHz and a zero-delay second-order correlation function of g(2)(0) = 0.08 is realized on the basis of these photonic nanostructures. The degree of indistinguishability of consecutively emitted photons measured in Hong-Ou-Mandel interferometry under above-barrier excitation is about 30%.

The processes of electron spin dynamics in a hybrid nonresonance structure, which includes a layer of a diluted magnetic II–Mn–VI semiconductor and an asymmetric quantum well (QW) of a nonmagnetic III–V semiconductor, are experimentally studied. The nonresonance of the structure is determined by the fact that the level of the ground state of the magnetic layer falls into the range of the excited states of the nonmagnetic QW. The electron polarization in the ground thermalized state of QW is found not to depend on the magnetic part of the structure. However, the magnetic part affects the electron polarization in the excited state via spin injection from the magnetic semiconductor and the mixing of the electronic states of the magnetic and nonmagnetic subsystems of the structure. The possibility of controlling the polarization of an electron spin by carrier excitation toward the region of mixed states along with the absence of depolarizing influence of the magnetic semiconductor on carriers in the thermalized state of QW can be applied to design new spintronic devices along with those that use spin injection, optical orientation, and depolarization.

We report on molecular beam epitaxial growth and properties of InAs/In 0.66 Ga 0.34 As/In 0.77 Al 0.23 As metamorphic quantum wells (QWs) with submonolayer InSb insertions grown on GaAs(0 0 1) substrates. InAlAs metamorphic buffer layers with linear and convex profiles are used to match gradually the lattice parameter from GaAs one to that of In 0.77 Al 0.23 As barriers, with the latter profile showing the better structural quality. A single type-II InSb insertion in the InAs QW shifts the photoluminescence (PL) peak maximum well beyond 3 μm due to the recombination of holes localized in the InSb well with electrons confined in the InAs/InGaAs QW. The mid-infrared PL in the structures with and without InSb insertion survives up to room temperature.

Metamorphic InAs/InGaAs/InAlAs quantum wells with submonolayer InSb insertions have been grown for the first time by molecular beam epitaxy on GaAs (001) substrates using a graded InAlAs buffer layer with increasing In composition. The given nanoheterostructures demonstrate an intense photoluminescence at a wavelength of over of over 3 μm (80 K), which is shifted toward longer wavelengths as compared with that of the structures without InSb insertions.

A circularly polarized magneto-photoluminescence (magneto-PL) technique has been applied to investigate the Zeeman effect in InAs/InGaAs/InAlAs quantum wells (QWs) in the Faraday geometry. Structures with different thicknesses of the QW barriers have been studied in the magnetic field parallel and tilted with respect to the sample normal. The effective electron-hole g-factor has been found by measurement of splitting of polarized magneto-PL lines. Lande factors of electrons have been calculated using the 14-band k.p method, and the g-factor of holes was determined by subtracting the calculated contribution of the electrons from the effective electron-hole g-factor. Anisotropy of the hole g-factor has been studied applying the tilted magnetic field. Published by AIP Publishing.

Exciton photoluminescence spectra, photoluminescence excitation spectra, and magnetophotoluminescence spectra of single (GaAs/AlGaAs/ZnMnSe) and double (GaAs/AlGaAs/ZnSe/ZnCdMnSe) heterovalent quantum wells formed by molecular beam epitaxy are studied. It is shown that the exciton absorption spectrum of such quantum wells mainly reproduces the resonant exciton spectrum expected for usual quantum wells with similar parameters, while the radiative exciton recombination have substantial distinctions, in particular the additional localization mechanism determined by defects generated by heterovalent interface exists. The nature of these localization centers is not currently clarified; their presence leads to broadening of photoluminescence lines and to an increase in the Stokes shift between the peaks of luminescence and absorption, as well as determining the variation in the magnetic g factor of bound exciton complexes.

The features of growth of GaInAsSb alloy with In content as high as 25 mol % lattice-matched to GaSb by molecular beam epitaxy are studied. These alloys are promising for use as the active region of photodetector structures of the mid-infrared range. The results of the study of these alloys by double-crystal X-ray diffractometry, scanning electron microscopy, and photoluminescence are presented. It is shown that the Ga x In1 − x As y Sb1 − y alloys with x < 0.8 grown at 500°C show the degradation of structural and optical properties as the layer thickness is increased. In layers with thicknesses above the critical one, spinodal decomposition is observed in complete agreement with thermodynamic calculations of the location of the boundaries of immiscibility regions. The possibilities to optimize the molecular beam growth of the Ga x In1 − x As y Sb1 − y alloys (x < 0.75) with high optical and structural quality, as well as the characteristics of photodetectors based on the GaInAsSb/AlGaAsSb heterostructures, are discussed.

GaAs/GaSb type-II quantum-dot heterostructures were grown by molecular-beam epitaxy. The circularly polarized photoluminescence of these samples in a magnetic field up to 4.7 T in the Faraday configuration was investigated. It was found that the emission from quantum dots in a magnetic field is σ−-polarized, which corresponds to the electron-spin component along the magnetic-field vector of +1/2. The degree of polarization increases with increasing excitation intensity. The observed effect is explained in terms of spin injection from the GaSb matrix, where spin orientation appears owing to the Zeeman splitting of the conduction band. An increase in the degree of polarization occurs due to a reduction in the charge-carrier radiative lifetime in type-II quantum dots with increasing excitation level.

We report on the spectroscopic magnetooptical studies of spin dynamics in diluted magnetic semiconductor (DMS) GaAs / AlGaAs / ZnSe / ZnCdMnSe heterovalent double quantum wells (QW). The transients of circularly polarized photoluminescence in an external magnetic field are detected in the structures with different widths of the GaAs QW. The analysis of the data, performed within the rate-equation model, has allowed separate estimations of the spin relaxation rate of localized electrons and holes. The spin flip of the electrons confined in the DMS ZnCdMnSe QW is faster than 20 ps, whereas the spin flip of the heavy hole localized in the GaAs QW is as long as ~9 ns. The long spin flip of the holes is presumably governed by their strong 3-dimensional localization.

Magnetooptical studies of heterostructures with type-II InSb quantum dots in the InAs matrix grown by molecular beam epitaxy are carried out. Unusual behavior of magnetophotoluminescence from quantum dots measured in the Faraday geometry in the samples with multiple planes of quantum dots is found. Specifically, the peak with σ− polarization, which corresponds to transitions of electrons with s = +1/2, has a higher energy than the σ+ peak corresponding to s = −1/2, which contradicts the negative value of the electron g factor both in the InAs matrix and in the InSb quantum dot. The effect can be interpreted as the result of competition of two channels of radiative recombination, which differ by the initial states of electrons belonging either to the InSb quantum dots or to shallow-level donors in the InAs matrix.

In studying circular-polarized photoluminescence, a high degree of spin orientation of electrons is observed in the n-type region of an InAs-based diode structure in a magnetic field in the Faraday geometric lay-out of the experiment. The degree of polarization is as high as 90% in the field of 2 T. In contrast, the degree of polarization in conventional InAs layers without a p-n junction is not higher than 20% in fields as high as 4 T. This effect is attributed to the built-in field of the p-n junction: the built-in field prevents localization of non-equilibrium electrons at shallow donor centers and, thus, allows orientation of electron spins due to Zeeman splitting in the conduction band.

The electroluminescence and photoluminescence of bulk n-InAs with a high concentration of donors (N d ≈ 5 × 1016 cm−3) is studied experimentally in magnetic field in the Faraday layout of the experiment. Under the conditions of electrical injection, the photon energy corresponding to the electroluminescence peak exceeds the energy band gap E g. When a magnetic field is applied, the energy of the peak becomes lower than E g, and the peak splits into two circular-polarized components. The splitting depends on the injection current. In moderate magnetic fields (about 2 T), the splitting can be much more profound than the calculated splitting corresponding to the well-known g factor of electrons in InAs. The effect is attributed to different degrees of magnetic freezing-out of electrons with different spin orientation. The maximum in the dependence of the degree of polarization of photoluminescence on the magnetic field and the behavior of the photoluminescence line width support the model suggested.

The technique of preparation of nanostructures with InSb quantum dots in an InAs(Sb) matrix, emitting in the mid-IR range upon optical and injection pumping, by molecular beam epitaxy is considered and the structural and optical properties of these nanostructures are investigated. The characteristics of the first injection lasers based on III–V/II–VI hybrid heterostructures with InSb/InAs(Sb) quantum dots in the active region are reported.

We report on a magneto-photoluminescence (PL) study of Zeeman effect in Mn modulation-doped InAs/InGaAs/InAlAs quantum wells (QW). Two PL lines corresponding to the radiative recombination of photoelectrons with free and bound-on-Mn holes have been observed. In the presence of a magnetic field applied in the Faraday geometry, both lines split into two circularly polarized components. While temperature and magnetic field dependence of the splitting are well described by the Brillouin function, providing an evidence for exchange interaction with spin polarized manganese ions, the value of the splitting exceeds by two orders of magnitude the value of the giant Zeeman splitting estimated for the average Mn density in QW obtained by the secondary ion mass spectroscopy.

We report on design, fabrication by molecular beam epitaxy, and photoluminescence (PL) studies of III-V/II-VI heterovalent structures containing a GaAs/AlGaAs/ZnSe/ZnCdMnSe double quantum well (QW) ...

We report on design, fabrication by molecular beam epitaxy, and photoluminescence (PL) studies of GaAs/AlGaAs/ZnSe/ZnCdMnSe double quantum wells (QWs), where resonant electronic coupling occurs through a heterovalent interface. The resonant conditions achieved in the properly designed sample facilitate penetration of the electron wave function from the nonmagnetic GaAs QW into the diluted magnetic semiconductor ZnCdMnSe QW. It results in the sign reversal and drastic increase of a GaAs QW excitonic g factor. The exciton spin splitting observed in the magneto-PL spectra is in general agreement with the calculation performed within the envelope function approximation, taking into account both the inter-well electron coupling and Brillouin-like paramagnetic behavior of the Mn2+ ions.

Molecular beam epitaxial growth of InSb sub-monolayer insertions in an InAs matrix, exhibiting intense mid-IR photoluminescence (PL) up to room temperature, is reported. The InSb insertions are fabricated by an exposure of the InAs surface to an antimony Sb 4 flux. The nominal thickness of the insertions grown at different temperatures (400-485 °C) changes in the 0.6-1 monolayer range, resulting in the emission wavelength variation from 3.9 to 4.3 μm at 300 K. An integral PL intensity drop from 80 to 300 K does not exceed 20 times. The laser emission at a wavelength of 3.08 μm (T=60K) with the threshold current density of 3-4kA/cm 2 under pulse injection pumping has been demonstrated in a hybrid p-AlGaAsSb/InAs/n-CdMgSe double heterostructure with the multiple type II InSb/InAs nanostructures in the active region.

We report on molecular beam epitaxy (MBE) growth and luminescence properties of tensile-strained type-II GaAs/ GaSb 1-x As x (0

Al x In 1-x As y Sb 1-y alloys lattice matched to InAs with an Al content up to x = 0.25 have been grown by molecular beam epitaxy on InAs (001) substrates and studied by double-crystal X-ray diffraction, scanning electron microscopy and photoluminescence (PL) spectroscopy. Thermodynamic stability of these alloys at typical MBE temperatures has been revised. It has been found that AlInAsSb alloys with x ∼ 0.15, grown at temperatures below 470°C, exhibit spinodal decomposition in good agreement with the calculated chemical instability gap boundary. However, the alloys with x ∼ 0.2 grown at higher temperature (above 500°C) have exhibited no decomposition features and demonstrate bright PL at 80K.

We report on the molecular beam epitaxy (MBE) growth and luminescence properties of tensile-strained type II GaAs/GaSb 1− x As x (0 x 1− y Sb y alloyed quantum wells (QWs) or self-organized formation of quantum dots (QDs). Both QW and QD nanostructures exhibit bright photoluminescence in the 1.5–2.2 μm range. AlGaSbAs laser diodes with GaAs/GaSb nanostructures in the active region have also been fabricated. The laser diode incorporating a 1.1 ML-GaAs/13 ML-GaSb superlattice in the active region shows room-temperature lasing at a wavelength of 1.85 μm under pulsed mode operation.

Zn(Mn)Te/Cd(Mn)Se quantum well heterostructures have been grown pseudomorphically on InAs(001) substrates using original InAs surface preparation techniques. The structures demonstrated bright PL in the 1-1.3 eV range and the effect of giant Zeeman splitting in the external magnetic field.

We present a time-resolved experimental study of excitonic magnetic polaron (EMP) dynamics in type II quantum wells ZnMnSe/ZnSSe. Two photoluminescence peaks were observed, which reflects coexistence of localized excitons and EMPs in the same sample. This was possible due to the competition of two localization mechanisms - magnetic localization of heavy holes in the ZnMnSe layers and non-magnetic localization of electrons in the ZnSSe layers.

InAs quantum wells (QWs) with AlAsSb and CdMgSe asymmetric barriers have been fabricated by a two-step molecular beam epitaxy on InAs(100) substrates. A 5-monolayer-thick ZnTe layer has been introduced between the InAs and CdMgSe layers as a buffer of the II–VI growth initiation. Ex-situ S-passivation technique applied to the uncapped InAs surface provides formation of defect free III–V/II–VI heterovalent interface. Photoluminescence study proves a strong type I band line-up at the ZnTe-mediated InAs/CdMgSe interface with the conduction and valence band offsets of about 0.6 eV and 1.0 eV, respectively. Transport properties of two-dimensional electron gas confined in a 16-nm-thick AlAsSb/InAs/ZnTe/CdMgSe QWs grown on GaAs (100) are compared with those of pure III–V 2DEG structures. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We report on the development of a novel design of a mid-IR laser combining III–V and II–VI compounds in a “hybrid” double heterostructure. It possesses large (∼1.5 eV ) potential barriers both for injected electrons and holes, suppressing their leakage from the active region, and provides strong optical confinement. An AlGaAsSb/InAs/CdMgSe laser diode with a III–V/II–VI heterovalent interface at the 0.6 μm -InAs active region has been grown by molecular beam epitaxy on an InAs substrate. Despite a far from optimal defect density at the CdMgSe/InAs interface and high losses inherent for bulk active region of the laser, the structure demonstrates lasing at ∼2.8 μm (up to 100 K ) in the pulsed regime with a threshold current density of 3–4 kA/cm 2 . Type II InSb monolayer insertions into an InAs layer show bright photoluminescence at 3.8 μm (77 K ), confirming the great potential of the InAs-based nanostructure active region for longer wavelength applications.

The lasing of an injection-pumped p-AlGaAsSb/n 0-InAs/n-CdMgSe double hybrid heterostructure in the mid-IR range is demonstrated for the first time. The lasing wavelength λ is 2.775 µm, and the threshold current density J th=3–4 kA/cm2 at T=77 K. The structure grown by two-stage molecular-beam epitaxy is characterized by extremely high (∼1.5 eV) asymmetric potential barriers for electrons and holes in the InAs active region. The output power of spontaneous emission for round-mesa diodes at T=300 K was no less than 0.3 mW.

In this report we present the study, by means of low-temperature magneto-optical measurements, of the spin transport dynamics in a heterovalent MBE-grown III-V/II-VI structure under optical pumping. The structure consists of two coupled GaAs quantum wells (QWs) of 100 A and 50 A surrounded by (Al,Ga)As barriers, a heterovalent (Al,Ga)As/ZnSe interface, a 10 nm (Zn,Mn)Se spin aligner, and a 70 nm thick ZnSe cap layer. We obtain values of about 30% at 4.5 T for the degree of circular polarization. These results give some hints on the design improvements needed for higher spin-filtering efficiency. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Heterostructures with a single InAs1−xSbx/AlSb1−yAsy quantum well (QW) on (001) GaSb substrates have been grown by MBE and studied using X-ray diffraction, transmission electron microscopy, and photoluminescence (PL) spectroscopy. High-intensity PL was observed at a temperature of 80 K, with a peak half-width of 30–50 meV and a peak wavelength in the range from 2 to 4.5 µm, depending on the QW width, which varied between 4 and 20 nm, respectively. The fundamental absorption edge of such QWs was calculated for a wide range of alloy compositions, x and y. Good correlation between the experimental and calculated dependences of the band gap on the InAsSb/AlSbAs QW thickness was obtained.

We present results from a detailed study of spin injection in thin II-VI wide band gap semiconductor heterostructures by magnetooptical spectroscopy. It is shown that efficient spin alignment can ...

We report on effective injection of spin-oriented carriers from a semimagnetic semiconductor structure to a non-magnetic ZnCdSe/ZnSe quantum well (QW). A short-period ZnMnSe/CdSe fractional monolayer superlattice was used as a spin injector. The carriers are photo-generated in the semimagnetic region, spin-polarized via the effect of giant Zeeman splitting and then injected into the non-magnetic QW. The spin injection efficiency was estimated by circular polarization measurements of recombination emission from the QW. The maximal detected degree of the spin polarization is about 25%.

We report for the first time on molecular beam epitaxial growth of new hybrid Al(Ga)Sb/InAs/Cd(Mg)Se heterostructures and studies of their structural, luminescence and transport properties. The structures demonstrate intense photoluminescence (PL) in both visible and infra-red spectral regions. The results of luminescence and structural measurements indicate the rather high structural quality of the A3Â5/A2Â6 interface. Theoretical estimations of band line-ups in these structures predict type II band alignment for the InAs/CdSe interface, which transforms to type I with increasing the Mg content in a CdMgSe alloy. A valence band offset as large as 1.6 eV is expected at the InAs/Cd(Mg)Se interface. The results of electron transport measurements along the interface are in good agreement with the theoretical estimation.

The fabrication of new hybrid AlAsSb/InAs/Cd(Mg)Se heterostructures by molecular beam epitaxy and investigation of their structural, luminescent, and transport properties are reported for the first time. These structures show intense luminescence both in the infrared and in the visible regions of the spectrum. This factor, taken together with structural data, indicates a heterointerface of high quality between the III–V and II–VI layers. A theoretical estimate is made of the relative positions of energy bands in the proposed hybrid structures, indicating that the InAs/CdSe interface is a type-II heterojunction, whereas the InAs/Cd0.85Mg0.15Se interface is a type-I heterojunction with a large valence band offset ΔE v≈1.6 eV. The data obtained on the longitudinal electron transport at the InAs/Cd(Mg)Se heterointerface are in good agreement with the theoretical estimate.

Photoluminescence of Ga1−x In x As y Sb1−y (0.08

Resonance of the photo-emf induced by far-IR light in the presence of a magnetic field oriented parallel to the plane of the well is observed in a GaSb-InAs-GaSb semimetal quantum well. It is inferred that the effect is due to optical transitions between sublevels of the first size-quantization level.

Electron spin polarization up to 100% has been observed in type-II narrow-gap heterostructures with ultrathin InSb insertions in an InAs matrix via investigation of circularly polarized photoluminescence in an external magnetic field applied in Faraday geometry. The polarization degree decreases drastically, changes its sign, and saturates finally at the value of 10% in the limit of either high temperature or strong excitation. The observed effect is explained in terms of strong Zeeman splitting of the electron conduction band in the InAs matrix and a heavy-hole state confined in the InSb insertion, due to a large intrinsic g-factor of both types of carriers. The hole ground state in a monolayer scale InSb/InAs quantum well, calculated using a tight-binding approach, fits well the observed emission wavelength. Temperature dependence of the emission polarization degree is in good agreement with its theoretical estimation performed in the framework of a proposed phenomenological model., 19 pages, 9 figures

A mid-IR laser based on a hybrid pseudomorphic AlGaAsSb/InAs/CdMgSe heterostructure with a III–V/II–VI heterovalent interface at the 0.6-μm-InAs active region has been fabricated by molecular-beam epitaxy on p+-InAs substrate. It provides ∼1.5-eV asymmetric barriers for both electrons and holes in InAs, inhibiting carrier leakage from the active region. Despite a nonoptimal defect density at the CdMgSe/InAs interface (106–107 cm−2), the structure demonstrates lasing at ∼2.78 μm (up to 100 K) under pulse injection pumping with the threshold current density of 3–4 kA/cm2. The proposed design is promising for high-power mid-IR lasers operating at room temperature.

We report on the study of spin-polarized electric currents in diluted magnetic semiconductor (DMS) quantum wells subjected to an in-plane external magnetic field and illuminated by microwave or terahertz radiation. The effect is studied in (Cd,Mn)Te/(Cd,Mg)Te quantum wells (QWs) and (In,Ga)As/InAlAs:Mn QWs belonging to the well known II-VI and III-V DMS material systems, as well as, in heterovalent AlSb/InAs/(Zn,Mn)Te QWs which represent a promising combination of II-VI and III-V semiconductors. Experimental data and developed theory demonstrate that the photocurrent originates from a spin-dependent scattering of free carriers by static defects or phonons in the Drude absorption of radiation and subsequent relaxation of carriers. We show that in DMS structures the efficiency of the current generation is drastically enhanced compared to non-magnetic semiconductors. The enhancement is caused by the exchange interaction of carrier spins with localized spins of magnetic ions resulting, on the one hand, in the giant Zeeman spin-splitting, and, on the other hand, in the spin-dependent carrier scattering by localized Mn2+ ions polarized by an external magnetic field., 14 pages, 13 figures

Magneto-optical spectroscopy in combination with tunable laser excitation is employed to study exciton spin alignment and injection in ZnMnSe/ZnCdSe quantum structures. This approach enables us to selectively create preferred spin orientation and to separately monitor subsequent spin injection from individual spin states, thus shedding light on a possible source of spin loss. It is shown that the limited spin polarization in a nonmagnetic quantum well due to spin injection from a ZnMnSe-based diluted magnetic semiconductor (DMS) is not caused by a limited degree of spin alignment in the DMS, which is in fact complete, but rather occurs during subsequent processes.

We report growth as well as optical and structural studies of a new type of a GaAs/GaSb heterostructure, with 1–3 monolayer thick GaAs layers embedded within unstrained GaSb. In such structures the GaAs layer is under tensile stress, in contrast to the situation in which self-organized growth of quantum dots is commonly observed. The structure emits light in the 2 μm wavelength range. The emission characteristics are explained by a combination of quantum confinement effects and localization on nanoscale potential fluctuations.

We report on microwave (mw) radiation induced electric currents in (Cd,Mn)Te/(Cd,Mg)Te and InAs/(In,Ga)As quantum wells subjected to an external in-plane magnetic field. The current generation is attributed to the spin-dependent energy relaxation of electrons heated by mw radiation. The relaxation produces equal and oppositely directed electron flows in the spin-up and spin-down subbands yielding a pure spin current. The Zeeman splitting of the subbands in the magnetic field leads to the conversion of the spin flow into a spin-polarized electric current., 3 pages, 4 figures

A new design of InSb photodetectors in the form of planar spirals is suggested and studied. This design enables fabrication of high-sensitive photodetectors with the responsivity peaks corresponding both to the interband and intraband transitions of electrons.

Diluted magnetic semiconductor heterovalent AlSb/InAs/ZnMnTe quantum well (QW) structures with an electron channel have been designed and grown applying molecular-beam epitaxy. The enhanced magnetic properties of QWs as a result of the exchange interaction with Mn2+ ions, are proved by measuring the microwave radiation induced spin polarized electric currents.

Circular‐polarized magneto‐photoluminescence of InSb/InAs type‐II quantum dots has been investigated at a magnetic field applied in the Faraday geometry in the wide range of the excitation intensity. It was observed that under condition of the low excitation (∼1 mW in a spot of 1 mm diameter) luminescence from quantum dots is 100% polarized even at the moderate magnetic field of 4T. Increase of excitation results in diminishing polarization and even change of its sign at the power above ∼100 mW. The effect is explained in terms of full electronic spin polarization in the conduction band due to the Zeeman effect in InAs matrix and power‐dependent contribution into optical recombination of the pure heavy hole states or the combined heavy‐light hole states emerged in InSb/InAs quantum dots.

A hybrid double heterostructure with large asymmetric band offsets, combining AlAsSb/InAs (as a III–V part) and CdMgSe/CdSe (as a II–VI part), has been proposed as a basic element of a midinfrared laser structure design. The p-i-n diode structure has been successfully grown by molecular beam epitaxy and has exhibited an intense long-wavelength electroluminescence at 3.12 μm (300 K). A less than 10 times reduction of electroluminescence intensity from 77 to 300 K indicates an efficient carrier confinement in the InAs active layer due to high potential barriers in conduction and valence bands, estimated as ΔEC=1.28 eV and ΔEV∼1.6 eV. The type of band lineups at a coherent InAs/Cd1−xMgxSe interface is discussed for 0⩽x⩽0.15.

The photon-momentum-dependent current in semimetallic GaSb/InAs/GaSb quantum wells in a magnetic field perpendicular to the 2D layer has been studied. The photocurrent was measured either parallel or perpendicular to the wave vector κ component along the 2D layer. In both cases two clearly pronounced resonances have been observed: the first one at the cyclotron resonance field H = Hc, the second one at the first subharmonic field H = 1 2 H c . However, only a resonance close to H = Hc is observed in the absorption coefficient. A classical theory which describes the experimental data well, has been suggested. Using a quantum model we interpret the resonance currents at H = 1 2 H c as one more manifestation of a fundamental phenomenon recently discovered — quantum interference resonant photocurrent.

Magnetooptical studies of InSb type-II quantum dots (QDs) grown by molecular beam epitaxy (MBE) in an InAs matrix have been done. Unusual behaviour of photoluminescence from QDs measured in Faraday geometry was observed in the samples with multiple sheets of QDs. In particular, the σ-polarized peak originating from optical transitions of electrons with s=+1/2 has higher energy than the σ+ peak which corresponds to s=−1/2 that contradicts negative value of electronic g factor in InAs and InSb. We explain the effect in terms of competition of two channels of radiative recombination. They differ in initial electronic states that are attributed to electrons localized by InSb QDs and shallow donors in an InAs matrix.

Photoluminescence (PL) has been studied in InAs diode structures grown by molecular beam epitaxy (MBE). In contrast to an InAs homogeneous layer, the p‐n structure in a magnetic field applied in Faraday geometry demonstrates very high degree of PL circular polarization, which exceeds 80% in the field as low as 1T at T=2K (bulk layer gives only ∼20% in the range of fields up to 4T). The polarization decays relatively slow with temperature. About 20% of the polarization degree was observed at the temperature as high as 50K in a magnetic field 2T. We believe that the effect originates from a strong built‐in electric field of the p‐n junction, that counteract the localization of photoexcited electrons on donors and enables effective spin alignment due to the Zeeman effect in the InAs conduction band.

Time‐resolved magneto‐photoluminescence spectroscopy is applied to elucidate dynamics of excitons in GaAs/AlGaAs/ZnSe/ZnCdMnSe heterovalent double quantum wells (QW). An essential slowdown of the recombination rate was observed, resulting from exciton localization due to the compositional disordering at the AlGaAs/ZnSe heterovalent interface. It was found that both exciton lifetime and spin lifetime can be controlled by varying the detuning of the single‐QW electron levels.

We report on time-resolved photoluminescence studies of exciton dynamics in a ZnMnSe/ZnSSe type-II quantum well. Strong separation of the electrons, confined to the nonmagnetic semiconductor ZnSSe, ...

We report on design, fabrication, and magnetooptical studies of a III-V/II-VI hybrid structure containing a GaAs/AlGaAs/ZnSe/ZnCdMnSe double quantum well (QW). The structure design allows one to tune the QW levels into the resonance, thus facilitating penetration of the electron wave function from the diluted magnetic semiconductor ZnCdMnSe QW into the nonmagnetic GaAs QW and vice versa. Magneto-photoluminescence studies demonstrate level anticrossing and strong intermixing resulting in a drastic renormalization of the electron effective g factor, in perfect agreement with the energy level calculations., Comment: 4 pages, 5 Postscript figures, uses revtex4