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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 heterointerface fundamentally changes the nature of these recombination processes with respect to the bulk material differently, depending on the type of heterojunction. Studying the electroluminescence of type-I and type-II light-emitting diode (LED) heterostructures based on InAsSb/InAs(Sb,P) quantum wells is presented. An increase in the relative efficiency of radiative recombination in the type-II heterostructure due to the suppression of Auger recombination favors the formation of intense stimulated emission in such heterostructures at low temperatures (4.2–70 K). [ABSTRACT FROM AUTHOR]

The results of a study in the temperature range 4.2–300 K of the current–voltage characteristics of light emitting diode (LED) heterostructures with an active region based on InAsSb solid solutions and InAsSb/InAs or InAsSb/InAsSbP quantum wells (QWs) are presented. The carrier-transport mechanisms depending on the temperature and heterostructure design are determined. It is shown that charge transport across the heterostructures is governed by the diffusion and recombination mechanisms at temperatures close to 300 K; in the temperature range 4.2–77 K, the contribution of the tunneling mechanism is observed. For an InAs/InAs/InAs0.15Sb0.31P0.54 heterostructure, an additional carrier-transport channel is observed. It is shown that the presence of 108 InAs0.88Sb0.12/InAs QWs in the active region leads to an increase in leakage currents across the heterojunction in the whole temperature range, which is likely related to carrier tunneling. [ABSTRACT FROM AUTHOR]

The results of studying the optical transmission, photoconductivity, photoluminescence, and X-ray diffraction of HgCdTe solid-solution samples with a high content of CdTe (molar fraction 0.7–0.8), grown by molecular-beam epitaxy (MBE) and liquid-phase epitaxy (LPE), are presented. It is shown that the material under study shows a significant degree of disorder of the solid solution, which is greater in structures grown by MBE on GaAs substrates, compared with the LPE-grown films. A study of the photoluminescence reveals states in the band gap, previously considered untypical of HgCdTe films grown on GaAs substrates, but typical only of films grown on Si. On the whole, the high quality of the material with a high CdTe content, grown by MBE and used to create the HgTe/HgCdTe nanostructures currently in high demand, is confirmed. [ABSTRACT FROM AUTHOR]

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 energy, which is the case for InAs, InAsSb solid solutions, etc. Our results are compared with simplified expressions for recombination rates, frequently used in publications. It is shown that the nonparabolicity of the electronic structure should be taken into account in calculations of the recombination rates. As an example, the temperature dependences of the charge-carrier lifetimes governed by radiative and non-radiative processes are calculated for InAsSb solid solutions. [ABSTRACT FROM AUTHOR]

The spatial and temporal dispersion of the dielectric function of the electron gas in quasi-2D quantum nanostructures has been studied. Analytical expressions for the dielectric function for a quantum well in the form of a δ function and a rectangular well of finite depth are derived for the first time. A criterion for transition to strictly 2D and strictly 3D cases was obtained. [ABSTRACT FROM AUTHOR]

The temperature dependence of the threshold current in GaInAs-based laser structures has been studied in a wide temperature range (4.2≤T≤290 K). It is shown that this dependence is monotonic in the entire temperature interval studied. Theoretical expressions for the threshold carrier density are derived and it is demonstrated that this density depends on temperature linearly. It is shown that the main contribution to the threshold current comes from monomolecular (Shockley–Read) recombination at low temperatures. At T > 77 K, the threshold current is determined by radiative recombination. At higher temperatures, close to room temperature, Auger recombination also makes a contribution. The threshold current grows with temperature linearly in the case of radiative recombination and in accordance with T 3 in the case of Auger recombination. © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

We have studied electroluminescence in n-GaSb/ n-AlGaAsSb/ n-GaInAsSb heterostructures with isotype heterojunctions, in which the quantum efficiency of emission is increased due to the additional production of electron-hole pairs as a result of the impact ionization that takes place near the heterointerface. The impact ionization in such heterostructures is possible due to the presence of deep wells in the energy band structure. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) of HgCdTe films grown by molecular beam epitaxy (MBE) has been studied in the 1.5–1.8 μm wavelength range. The post-growth annealing of samples for 20 h at 270°C in an inert atmosphere leads to changes in the spectrum and intensity of luminescence. The spectral changes are related to an increasing homogeneity of the film composition in depth as a result of the mutual diffusion of alloy components. An increase in the room-temperature PL intensity is due to the improved structure of annealed films. [ABSTRACT FROM AUTHOR]

The phenomenon of conversion of the conductivity type in p-type samples of the Cd[sub x]Hg[sub 1 - x]Te (0.28 ≤ x ≤ 0.55) and Zn[sub x]Cd[sub y]Hg[sub 1 - x - y]Te solid solutions bombarded by low-energy argon ions was studied. It is shown that a necessary condition for the conversion effect in Cd[sub x]Hg[sub 1 - x]Te with 0.28 ≤ x ≤ 0.39 is ion neutralization in the bombarding beam. The dependence of the conversion layer thickness in Cd[sub x]Hg[sub 1 - x]Te on the solid solution composition agrees with that predicted by the diffusion model of ion-bombardment-induced conversion of the conductivity type. [ABSTRACT FROM AUTHOR]

The results of the study of optical and structural properties of epitaxial InAs layers grown on an n-InAs substrate, and spectral and electrical properties of light-emitting diode (LED) heterostructures with an InAs active layer and various design and chemical composition of barrier layers are presented; the properties of heterostructures were studied in the temperature range 4.2−300 K. A significant influence of the degree of substrate doping and the properties of heterointerfaces on the form of emission spectra and power characteristics of heterostructures is shown. The mechanisms of the carrier transport are studied, and the prevalence of the diffusion component of the current at temperatures above 200 K and the presence of the tunneling component at lower temperatures are shown. [ABSTRACT FROM AUTHOR]

The electroluminescence of the single unconfined type-II heterojunction p-GaInAsSb/p-InAs was investigated in the temperature range T = 4.2-77 K. As the temperature was reduced below T = 77 K, the luminescence bands with maxima at 311 meV (band A) and 384 meV (band B) were found to shift toward higher energies. At 4.2 K, the short-wave band split into two bands, B[sub 1] and B[sub 2]. These results are explained in terms of a model involving recombinations of electrons from the conduction band to an acceptor level of InAs, and also recombinations of electrons and holes localized in self-consistent quantum wells on either side of the heterojunction. [ABSTRACT FROM AUTHOR]

The electroluminescence appearing upon pulsed excitation in a solitary p-GaInAsSb/p-InAs typeII (broken-gap) heterostructure is investigated at T = 77 K. It is shown that just as in the case of excitation by a constant current, two emission bands with maxima corresponding to 384 and 311 meV, respectively, are observed in the spectra. The half-widths of the emission bands equal 18-19 meV. Time-resolved spectroscopy is used to evaluate the relaxation time of the nonequilibrium carriers, which amounts to 6-7 µs. The emission spectrum is calculated on the basis of the Kane model, and the radiative recombination time is estimated. The theoretical estimates are in reasonable agreement with experiment. [ABSTRACT FROM AUTHOR]

A study of the electroluminescence of asymmetric InAs/InAs1 – ySby/InAsSbP light-emitting diode heterostructures with a molar fraction of InSb in the ternary solid solution in the active region y = 0.15 and y = 0.16 in the temperature range 4.2–300 K is reported. It is found on the basis of experimental data that a staggered type-II heterojunction is formed at the InAs1 – ySby/InAs0.41Sb0.28P0.40 heterointerface. It is shown that interfacial radiative transitions at the type-II heterointerface make a dominant contribution in the temperature range of 4.2–180 K. This enables minimization of the temperature dependence of the operating wavelength of a light-emitting diode. [ABSTRACT FROM AUTHOR]

The results of comparative studies of the optical and structural properties of Hg0.7Cd0.3Te bulk crystals and epitaxial films grown by various methods are presented. The data of photoluminescence studies performed in the temperature range 4.2–300 K showed the similarity of the optical properties of different samples and indicated a significant disordering of the solid solution. According to X-ray diffraction data, however, the scale of the disordering was not directly related to the structural quality of the material. The prospects for using the material grown by various methods in optoelectronics applications are discussed. [ABSTRACT FROM AUTHOR]

The first results showing the possibility of manufacturing InAs/GaSb superlattices by the metal-organic chemical vapor deposition (MOCVD) method are presented. The possibility of manufacturing heterostructures with an InAs/GaSb strained superlattice with layer thicknesses of 2–4 nm is experimentally demonstrated. The 77-K electroluminescence spectra of the structures show a long-wavelength peak at around 5.0 μm (0.25 eV). This peak is probably associated with the strained superlattice because solid solutions that could form on the basis of composite compounds do not provide this carrier-recombination energy. [ABSTRACT FROM AUTHOR]

The electroluminescent characteristics of the InAs/InAs1–ySby/InAsSbP asymmetric light-emitting diode heterostructures with high InSb mole fraction in the active region (y > 0.09) in the temperature range 4.2–300 K have been studied. Stimulated emission was achieved in the wavelength range 4.1–4.2 μm at low temperatures (T < 30 K). It was found that the electroluminescence spectra were formed as a result of the superposition of contributions from different channels of radiative recombination of charge carriers near the type II heterointerface. The effect of the quality of the type II InAsSb/InAsSbP heterojunction on the radiative interface transitions with an increase in the content of InSb in the ternary solid solution is considered. [ABSTRACT FROM AUTHOR]

A study of defects in HgCdTe films grown by molecular-beam epitaxy on GaAs and Si substrates was performed. Variable-temperature photoluminescence (PL) and carrier lifetime measurements were carried out on as-grown films and films subjected to post-growth annealings. Films grown on GaAs substrates appeared to be mostly free from defects providing energy states within the bandgap, yet specific acceptor states were generated in these films under conditions associated with mercury deficiency. The properties of films grown on Si substrates were mostly governed by two types of uncontrolled defects. Relatively deep levels with energy 40 to 70 meV were revealed with the use of PL measurements, yet their effect on the lifetime was not traced. The lifetime value was rather determined by other type of defects with energy depth of ∼30 meV. Possible relation of these defects to the specifics of MBE growth of HgCdTe on Si substrates is discussed. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The spectral parameters of midinfrared LED heterostructures with an InAs active region were studied experimentally, calculated using MATLAB, and simulated in COMSOL Multiphysics. The obtained data were compared to reveal the mechanism of formation of the emission spectra of these heterostructures. The results confirm that simulation is a promising design tool for LED structures. [ABSTRACT FROM AUTHOR]

The capabilities of metalorganic vapor-phase epitaxy (MOVPE) in fabrication of structures with thin (1–2 nm) alternating InAs/GaSb layers on a GaSb substrate are studied. The characteristics of these structures were examined using transmission electron microscopy and methods of photo- and electroluminescence. It was found that two GaInAsSb solid solutions of different compositions were formed in the active regions of structures in the given growth conditions. The fabricated system was characterized by an emission wavelength of 4.96 μm at a temperature of 77 K. The results reveal new opportunities for bandgap engineering of semiconductor structures based on InAs/GaSb, which are designed for optoelectronic devices operating in the infrared range, provided by MOVPE. [ABSTRACT FROM AUTHOR]

The disordering in cadmium mercury telluride solid solution films grown by molecular beam epitaxy on Si and GaAs substrates has been examined by optical transmission and photoluminescence investigations. The effect of a fundamental decrease in the disordering scale under thermal annealing and possible interplay of the observed phenomena with defects typical of films grown by molecular beam epitaxy are discussed. [ABSTRACT FROM AUTHOR]

We have studied the influence of various postgrowth treatments (annealing in helium atmosphere or mercury vapor, low-energy ion etching) on the optical and photoelectrical properties of mercury cadmium telluride (Cd xHg1 − xTe) heteroepitaxial structures for the photo- and optoelectronic devices operating in the middle infrared range (3–5 μm). It is established that the annealing in mercury vapor is optimum for improving the photoluminescence characteristics in this range. [ABSTRACT FROM AUTHOR]