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The n+-InAs/n0-InAs1 –ySby/p-InAsSbP heterostructures with asymmetric band offsets at the heteroboundaries of the active region have been grown by vapor-phase epitaxy from organometallic compounds on InAs substrates. The forward branch of the current–voltage characteristics of the obtained heterostructures at low temperatures has segments with the tunneling conduction. The energy-band diagram of the double InAs/InAs1 –ySby/InAsSbP heterostructure is calculated in the range of compositions (y < 0.2) of the narrow-gap active region. The InAs1 –ySby/InAsSbP heterojunction is shown to be a II type heterojunction in this composition range. The electroluminescence observed in the experiment for the n+-InAs/n0-InAs1 ‒ySby/p-InAsSbP heterostructures with the active region in compositions y > 0.14 is due to interface radiative transitions with participation of localized hole states at the II type heteroboundary. [ABSTRACT FROM AUTHOR]

The peculiarity of planar quantum magnetotransport in the type II broken-gap p-GaInAsSb/p-InAs heterostructures at high magnetic fields has been investigated. The structure of the hybridized energy spectrum of a two-dimensional semimetal channel at a single type II broken-gap heterointerface was considered in dependence on the composition of the quaternary solid solution. A transition from a conducting state to a dielectric state (quantum insulator) for a 2D-semimetal channel at the heteroboundary was observed in quantizing magnetic fields under the condition of simultaneous filling of the first Landau levels for 2D-electron and interface hole states. [ABSTRACT FROM AUTHOR]

Mid-infrared photoluminescence has been observed from interface transitions in high quality, abrupt P–Ga[sub 0.84]In[sub 0.16]As[sub 0.22]Sb[sub 0.78]/p-InAs heterojunctions grown by liquid phase epitaxy from an In-rich melt. The Ga[sub 0.84]In[sub 0.16]As[sub 0.22]Sb[sub 0.78] quaternary epitaxial layer was unintentionally doped and grown lattice matched on to a (100) oriented p-type InAs substrate, resulting in a P–p isotype heterojunction. The photoluminescence emission spectra were investigated and exhibited three pronounced emission bands in the spectral region from 0.30 to 0.68 eV; hν[sub 1]=0.317 eV, hν[sub 2]=0.380 eV, and hν[sub L]=0.622 eV. The emission band hν[sub 1] was identified with radiative transitions between electron and hole quantum well subbands in the semimetal channel at the P–GaIn[sub 0.03]As[sub 0.10]Sb/p-InAs interface, while the hν[sub 2] band originates from radiative transitions involving deep acceptor states in the InAs substrate. The high-energy recombination hν[sub L] is characteristic of the Ga[sub 0.84]In[sub 0.16]As[sub 0.22]Sb[sub 0.78] bulk quaternary layer. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This overview is devoted to the discovery, development of the technology, and investigation of III–V semiconductors performed at the Ioffe Institute, where the first steps in fabricating III–V semiconductors were taken in 1950 and investigations into their fundamental properties were begun under the leadership of two outstanding scientists—Nina Aleksandrovna Goryunova and Dmitry Nikolayevich Nasledov. Further development of these investigations is reflected in the works of followers and pupils of D.N. Nasledov, who have worked and continue to work at subsidiaries of the Ioffe Institute. The contribution of these investigations to studying heterostructures based on III–V compounds as well as to the development of semiconductor devices for electronics, optoelectronics, and photonics is considered. [ABSTRACT FROM AUTHOR]

The authors studied the features of planar and vertical quantum magnetotransport in the broken-gap type II p-GaInAsSb/p-InAs heterostructure. This study reveals the structure of the hybridized energy spectrum of a two-dimensional semi-metallic channel at a single broken-gap type II heterointerface. It is demonstrated that an energy diagram of Landau levels can be visualized for a hybridized electron-hole system taking into account their spin splitting and mutual intersections. [ABSTRACT FROM AUTHOR]

Abstract: Characteristic effects of magnetic ordering and conduction in semiconductor heterostructures with a GaAs : Be/Ga0.84In0.16As/GaAs quantum well and manganese δ-layers of different thickness (from 0.4 to 2 monolayers) were studied based on analysis of magnetic field and temperature dependences, galvanomagnetic effects, and magnetization. An anomalous dependence of the conductivity on the manganese atoms concentration in the δ-layer was observed, which was due to a strong scattering of charge carriers in the structures with the low content of magnetic impurities. Magnetic properties of the heterostructures clearly indicated the magnetic ordering of the impurity system (saturation and hysteresis of the magnetization and fulfillment of the Curie-Weiss law at increasing temperature). Parameters of the magnetic subsystem allowed revealing different types of ordering in the systems with different concentrations of the magnetic impurity. Changing the concentration of the Mn admixture in the δ-layer was shown to influence significantly the conductivity and magnetism in the studied structures. [ABSTRACT FROM AUTHOR]

The effect of the interface roughness (IFR) scattering on the carrier mobility in type II broken-gap p-GaInAsSb/p-InAs heterostructures with self-consistent quantum wells at the interface has been studied experimentally. It was found that the low-temperature mobility decreases as μ∼d2 when the quantum well width at the interface changes from 400 to 50 Å upon raising the acceptor (Zn) doping level of the quaternary layer. It was established that the IFR scattering governs the low-temperature mobility in the two-dimensional electron channel at the heterointerface. The parameters of the IFR scattering, roughness height Δ=12 Å, and correlation length Λ=100 Å were evaluated on the basis of structural, photoluminescent, and magnetotransport data. [ABSTRACT FROM AUTHOR]

Arrays of coherent InSb quantum dots (QDs) have been fabricated by liquid-phase epitaxy on InAs substrates in the temperature range T = 420–450°C. The QDs with a density of (0.9−2) × 1010 cm−2 were 3 nm high and 13 nm in diameter. A bimodal QD size distribution was observed, which was accounted for by a combined growth mechanism of these nanoobjects. Structural characteristics of a separate InSb QD formed on the InAs surface were studied for the first time by atomic-force and transmission electron microscopies. Moire fringes were observed for the first time for QDs in the InSb/InAs system, with the moire period of 3.5 nm corresponding to InSb QDs without an admixture of arsenic. [ABSTRACT FROM AUTHOR]

Layers of the GaSb1 − x As x alloy with arsenic content in the range x = 0.06–0.15 have been grown for the first time on InAs (100) substrates by metal-organic vapor-phase epitaxy. A new approach to the calculation of the band diagram of the GaSbAs alloy is suggested. It is demonstrated on the basis of magnetotransport measurements in p-GaSbAs/ p-InAs heterostructures and with the method suggested by the authors for the calculation of band diagrams for alloys in the GaSbAs system that, in the composition range under study, the GaSbAs/InAs heterojunction is a type II broken-gap heterojunction. [ABSTRACT FROM AUTHOR]

Magneto-photoluminescence in a single type-II broken-gap n-Ga0.94In0.06As0.13Sb0.87/ p-InAs heterostructure with a 2D electron channel at the heterointerface containing two occupied electron subbands has been studied in the spectral range 0.3–0.8 eV in high magnetic fields of up to 10 T at low temperatures ( T = 7 K). At photon energies in the range 0.5–0.8 eV, bulk photoluminescence from the layer of the n-GaInAsSb alloy was observed. In the low-energy part of the spectrum (0.3–0.45 eV), three narrow emission bands with photon energies hν a = 0.419 eV, hν b = 0.404 eV, and hν c = 0.384 eV and full widths at half-maximum FWHM = 4–7 meV were observed. These bands are due to radiative transitions of 2D electrons localized in the quantum well on the InAs side near the type-II heterointerface. The electron effective mass in the occupied subband E 2 was estimated to be m 2 = 0.027 m 0, which is close to the effective mass at the bottom of the InAs conduction band. [ABSTRACT FROM AUTHOR]

The first original results on the growth of quantum dots (QDs) in the InSb/InAs system by liquid phase epitaxy (LPE) are reported. The density and dimensions of QDs were studied by methods of scanning probe microscopy and atomic force microscopy. The surface density, shapes, and dimensions of LPE-grown nanoislands depend on the growth conditions (temperature, cooling rate, and solution melt-substrate contact time). In the interval of temperatures T = 420–445°C, homogeneous arrays of InSb quantum dots on InAs(100) substrates were obtained with an average height of H = 3.4 ± 1nm, a radius of R = 27.2 ± 7.5 nm, and a density of up to 1.9 × 1010 cm−2. [ABSTRACT FROM AUTHOR]

The formation of self-consistent quantum wells for electrons and holes in a P(N)-GaInAsSb/p-InAs broken-gap type II heterojunction with an abrupt planar interface (a transition layer of the order of 1.2 nm thick) upon variation of the type and level of doping of the semiconductors in contact is controlled by the overlap of the energy bands at the heterointerface. In a study of the vertical magnetotransport through a GaInAsSb/p-InAs broken-gap type II heterointerface it is shown that the increase of the localization of the two-dimensional electrons in the electron channel at the interface leads to the formation of a “soft” Coulomb gap in the tunneling density of states. In magnetic fields below 15 T at helium temperature a transition from the state with a “soft” Coulomb gap to an insulator state (a hard energy gap at a conductance value of σtun∼10-8 Ω-1) is observed under the condition that the Fermi level for the two-dimensional electrons lies in the interval between the lowest Landau levels for the ν=2 plateau on the ρxy curve. As the external bias across the heterojunction is increased, the threshold offset from the insulator state is due to one-electron tunneling between individual closed regions of extended electronic states of the Landau level closest to the Fermi level. [ABSTRACT FROM AUTHOR]

Conditions for the transition from the staggered heterojunction to the type-II broken-gap one were considered for isolated Ga1− x InxAsySb1− y /InAs(GaSb) heterostructures in relation to the quaternary alloy composition. Energy-band diagrams of such heterojunctions were estimated and energy band offsets Δ at the heterointerface were determined. It was experimentally found that the type-II broken-gap heterojunction in the Ga1− x InxAsySb1− y / p-InAs structure is observed in the entire range of composition parameters under study, 0.03 < x < 0.23, and becomes staggered in the range 0.3 < x < 1. In p-Ga1− x InxAsySb1− y / p-GaSb heterostructures with the indium content 0.85 < x < 0.92 in the solid phase, the p-type conductivity is observed, which is indicative of the staggered heterojunction. At x > 0.92, the contribution of electrons of the semimetal channel at the heterointerface to the total conductivity was observed, as well as the transition from the staggered heterojunction to the type-II broken-gap one. [ABSTRACT FROM AUTHOR]

The lasing of an injection-pumped p-AlGaAsSb/n[SUP0]-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[SUBth] = 3-4 kA/cm[SUP2] 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 atT = 300 K was no less than 0.3 mW. [ABSTRACT FROM AUTHOR]

Photoluminescence of Ga[sub 1-x]In[sub x]As[sub y]Sb[sub 1-y] (0.08 < x < 0.22) epilayers lattice-matched to InAs substrate was investigated for the first time at 80 K, and the band gap of solid solutions was evaluated experimentally. It was demonstrated that the intensity of the band-to-band radiative recombination for p-GaInAsSb undoped layers depends on the composition of the quaternary solid solution and is governed by the concentration of intrinsic structural defects. For an n-GaInAsSb:Te donor-doped layer, the band-to-band recombination band and an additional emission band were observed. The latter band is related to the radiative recombination via the deep acceptor level formed by an intrinsic complex V[sub Ga]Te with the activation energy E[sub DA] = 122 meV. [ABSTRACT FROM AUTHOR]

High-quality type II Ga[sub 0.83]In[sub 0.17]As[sub 0.22]Sb[sub 0.78]/InAs heterostructures based on GaSb-rich quaternary solid solutions were grown by liquid phase epitaxy on InAs(001) substrates. GaInAsSb epilayers were grown under planar two-dimensional growth conditions with abrupt and planar interfaces. The thickness of the transition layer on the Ga[sub 0.83]In[sub 0.17]As[sub 0.22]Sb[sub 0.78]/InAs interface enriched with In and Sb was 10-12 Å in perfect structures. The roughness of the upper boundary was entirely determined by the epitaxial-growth conditions and did not exceed 500 Å in structures with a layer thickness of about 2 µm. [ABSTRACT FROM AUTHOR]

Electroluminescence bistability is observed in a typ-II P-AlGaAsSb/p-InGaAsSb/ N-AlGaAsSbheterostructure with lightly doped cladding layers and a narrow-gap active region (the width of the band gap is E[sub g]= 326 meV at the temperature T = 77 K). A currentcontrolled negative differential resistance is observed in the forward branch of the currentvoltage characteristic. Strong narrowband electroluminescence (half-width ∼ 7 - 10 meV) is observed at the end of the negative differential resistance interval, where the photon energy at the radiation maximum exceeds the width of the band gap of the narrow-gap material by 50 meV. This phenomenon is attributed to the tunneling injection and indirect radiative recombination of carriers localized at the AlGaAsSb/InGaAsSb heterojunction. As the voltage is increased, radiative transitions in the bulk of the active region begin to provide the main contribution, and the radiation maximum jumps to the long-wavelength end. Tunneling injection structures of this kind can be used to construct highly efficient current-controlled lightemitting diodes. [ABSTRACT FROM AUTHOR]

Intense mid-infrared (λ∼2 μm) room temperature electroluminescence from metal organic vapor phase epitaxy (MOVPE) grown type-I single AlSb/InAsSb/AlSb quantum wells (QWs) is reported. The spectral position of the electroluminescent peaks is in good agreement with k·p envelope function calculation in the frame of four-band Kane’s model taking into account the intermixing of s and p states in the deep quantum well. A four times increase of the emission intensity with temperature increasing from 77 to 300 K can be explained by highly efficient radiative recombination of the electrons injected into the narrow AlSb/InAsSb/AlSb QW due to its specific design, leading to Auger process suppression. [ABSTRACT FROM AUTHOR]

Low-temperature photoluminescence (PL) study of liquid phase epitaxy grown undoped and Sn doped GaIn[sub 0.16]As[sub 0.22]Sb layers lattice matched to InAs is reported. The quaternary solid solutions Ga[sub 1-x]In[sub x]As[sub y]Sb[sub 1-y] are promising materials for the fabrication of optoelectronics devices operating in the spectral range 3–5 μm because these alloys can form type II heterojunctions both with staggered and broken-gap alignment. The band structure engineering of these devices requires the knowledge of energy gaps and mechanism of radiative recombination transitions in the forbidden gap of cladding layers. The high quality quaternary GaIn[sub 0.16]As[sub 0.22]Sb epitaxial layers with low native defect concentration were grown lattice matched to InAs and their photoluminescence was studied at low temperatures. The emission band related to bound exciton was dominant. While the emission bands associated with the first ionization state of V[sub Ga]Ga[sub Sb] vacancy-antisite defect with activation energy ΔE[sub A]=22 meV and unknown deep defect with ΔE[sub B]=46 meV were found besides the main PL peak ΔE[sub BE]=16 meV. It was established that Sn as an amphoteric impurity can form shallow donor levels. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The electroluminescent properties of quantum-well diode structures on staggered type-II heterojunctions in the InAs/GaSb system, obtained by molecular-beam epitaxy on InAs substrates, are investigated. Electroluminescence is observed in the spectral range 3-4 µm at T = 77 K. It is found that emission bands due to recombination transitions involving electrons from the size-quantization levels of both the self-matched quantum wells at the InAs/GaSb type-II heterojunction and of the square quantum wells in short-period superlattices. [ABSTRACT FROM AUTHOR]

Intense electroluminescence is observed for the first time in a AlGaAsSb/In[sub 0.9]Ga[sub 0.1]As[sub 0.89]Sb[sub 0.21]/ AlGaAsSb double heterostructure in the 3-4 µm wavelength range at T=77 K. The structure was grown on a GaSb substrate by liquid-phase epitaxy. The photon energy at the maximum of the narrow emission band with a half-width of 9-10 eV is h ν, = 387 meV which is 60 meV greater than the band gap of the narrow-gap InGaAsSb solid solution (E[sub g]= 326 meV). [ABSTRACT FROM AUTHOR]

Laser structures based on broken-gap type II p-GaInAsSb/n-InGaAsSb heterojunctions in the active region are proposed and studied. Lasing at 3.2-3.4 µm has been obtained in the temperature range 77-195 K with a threshold current density of 400 A/cm² at 77 K and a characteristic temperature T[sub 0] = 47 K. [ABSTRACT FROM AUTHOR]

Laser photooxidation is used to form a surface antimony layer on p-type GaSb and GaAs0.06Sb0.94. The emerged Sb/III-Sb interface is studied by a combination of the Raman and photoluminescence spectroscopy supported by Kelvin probe microscopy and atomic force microscopy. The laser power density controls the thickness and structure of the Sb layer. Laser photooxidation thickens the amorphous Sb layer that emerged after native oxide formation. The thickening decreases the bandgap photoluminescence intensity and increases surface band bending. Further increase in the laser power density forms a multilayered antimonene phase with a rhombohedral structure. The crystalline Sb layer decreases the surface band bending due to changes in the work function. For the crystalline layer, the PL intensity further decreases. The effective work function model explains the experimental results. Finally, the study shows that it is possible to modify surface optoelectronic properties with a submicrometer lateral resolution. [ABSTRACT FROM AUTHOR]

We report on the electroluminescent and I–V characteristics of the n-InAs/n-InAsSb/p-InAsSbP heterostructure grown by metalorganic vapor-phase epitaxy. In the spectral range of 0.23–0.29 eV, the high-intensity electroluminescence at a temperature of T = 77 K has been observed. The position of the maximum of the main emission band ( ~ 0.24 eV) has shown a noticeable blue shift with increasing forward bias. Based on the investigations, a conclusion about the existence of a type-II staggered heterojunction at the InAs0.84Sb0.16/InAs0.32Sb0.28P0.40 heterointerface has been drawn, which is confirmed by the calculated energy band diagram. [ABSTRACT FROM AUTHOR]

Asymmetric n-InAs/InAs(1 –y)Sby/p-InAsSbP heterostructures with a narrow-gap active layer and a composition range y = 0.09–0.16 were grown by vapor phase epitaxy from metalorganic compounds. Room-temperature electroluminescence was observed at a wavelength of up to λ = 5.1 μm at a spectral maximum. The study of low-temperature electroluminescence spectra provided the possibility to establish the existence of two radiative recombination channels caused by the nature of the InAsSb/InAsSbP heterointerface. The effect produced by the chemistry of the active layer on the composition of the grown barrier layer and the formation of the InAsSb/InAsSbP heterojunction with an increase in the antimony content in the InAsSb solid solution was demonstrated. [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]

Uniform arrays of the InSb quantum dots with a surface density of nQD = 2 × 109 cm–2 were obtained by liquid phase epitaxy on a matrix layer based on a multicomponent InGaAsSb solid solution lattice-matched with the GaSb substrate. The change in the composition of the cationic part of the matrix by using the epitaxial matrix layer allowed to lower the temperature of the epitaxy to T = 430°C and determined the shape of a typical InSb quantum dot in the form of a truncated cone with average values of height h = 3 nm and diameter d = 30 nm, which corresponded to the aspect ratio L = h/d = 0.1. [ABSTRACT FROM AUTHOR]

Single heterostructures of type II n+-InAs/n0-InAs0.59Sb0.16P0.25, based on an intentionally undoped epitaxial layer with an electronic type of conductivity are obtained by metalorganic vapor phase epitaxy (MOVPE). In the heterostructure, a transition layer of modulated composition is formed near the heterointerface in the bulk of the quaternary solid solution. The existence of a radiative recombination channel due to the presence of localized hole states in quantum wells formed in the transition layer near the heterointerface is shown. It is demonstrated that the maximum of the intensity of the electroluminescence spectrum of the heterostructure under study is rearranged when a forward external bias is applied. The results of this study can be used in the development of tunable light-emitting diodes operating in the midinfrared range of 2-4 μm. [ABSTRACT FROM AUTHOR]

Luminescent characteristics of asymmetric p-InAs/AlSb/InAsSb/AlSb/ p-GaSb type II heterostructures with deep quantum wells at the heterointerface are studied. The heterostructures were grown by metalorganic vapor phase epitaxy. Intense positive and negative luminescence was observed in the range of photon energies of 0.3–0.4 eV with a forward and reverse bias, respectively. Dependences of the spectra and intensities for positive and negative luminescence on the pumping current and on the temperature are studied in the range of 77–380 K. It is established that, at a temperature higher than 75°C, intensity of negative luminescence surpasses that of positive luminescence by 60%. The suggested heterostructures can be used as lightemitting diodes (photodiodes) with switched positive and negative luminescence in the mid-IR spectral range of 3–4 μm. [ABSTRACT FROM AUTHOR]

The electrical properties of epitaxial InAs and solid solutions based on it (InGaAsSb, InAsSbP, InAsGa, InAsP) have been investigated. It is shown that intentionally undoped crystals have n-type conductivity, which is determined by shallow donor impurities (E[sub 1] = 0.002-0.003 eV) and structural defects (E[sub 2] = 0.02-0.03 eV and E[sub 3] = 0.09-0.10 eV). It is shown that growth of epitaxial InAs using the neutral solvent Pb and also rare-earth elements makes it possible to reduce the electron density by almost an order of magnitude (to levels as low as 3 × 10[sup 15] cm[sup -3]) due to due to a decrease in the density of structural defects. [ABSTRACT FROM AUTHOR]

New possibilities of scanning electron microscopy, using secondary- and reflected-electron signals, for determining the position of heteroboundaries in long-wavelength laser structures are reported. The formation of the indicated signals in structures of mid-infrared-range lasers of a new type based on type-II GaInAsSb/InGaAsSb heterostructures as well as in the conventional InAsSb/InAsSbP heterostructures is analyzed. The observed characteristic features of the formation of secondary- and reflected-electron signals in these structures as compared with the well-studied AlGaAs/GaAs structures are explained. The results obtained are necessary for accurate determination of an important laser parameter — the position of the p-n junction. It is shown that it is best to use the reflected-electron signal. [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 design and technology for the fabrication of an asymmetric stepped InAs/InAs1 –ySby/InAsSbP heterostructure with an ultimate InSb content (up to y = 0.17) in the narrow-gap active region by vapor-phase epitaxy from metal-organic compounds are developed. The electroluminescence characteristics of long-wavelength LEDs based on the proposed heterostructure, which emits in the spectral range of 4.6–5.3 μm, are studied. A linear decrease in the quantum efficiency of the electroluminescence with increasing InSb content in the active layer of the LEDs obtained is revealed. The advantage of using the asymmetric heterostructure for fabricating LEDs with a working wavelength of more than 4.5 μm is shown. [ABSTRACT FROM AUTHOR]

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 ΔE[sub C]=1.28 eV and ΔE[sub V]∼1.6 eV. The type of band lineups at a coherent InAs/Cd[sub 1-x]Mg[sub x]Se interface is discussed for 0≤x≤0.15. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Ga0.84In0.16As0.22Sb0.78 quaternary solid solutions, lattice matched to InAs, were grown by liquid phase epitaxy on (100)-oriented p-InAs substrates from In-rich melt. The p-type Ga0.84In0.16As0.22Sb0.78 layers were intentionally undoped or slightly doped with Sn to the hole concentration about p∼5×1016 cm-3. This allowed us to obtain a high-mobility∼(3.5-5.0)×104 cm2 V-1 s-1 electron channel at the type II broken-gap p-Ga0.84In0.16As0.22Sb0.78/p-InAs heterointerface. Low-temperature (T=5 K) electroluminescence spectra exhibited two pronounced emission bands hν1=0.372 eV and hν2=0.400 eV under forward bias. The emission band hν2 was split into two lines and was attributed to interband transitions through acceptor and valence-band states in the bulk InAs, whereas emission band hν1 was ascribed to interface-related radiative transitions of electrons from the two-dimensional electron channel to the interface states at the p-Ga0.84In0.16As0.22Sb0.78/p-InAs heteroboundary. [ABSTRACT FROM AUTHOR]

The results of detailed study of the magnetotransport properties of broken-gap type II heterojunctions in a GaInAsSb/InAs(GaSb) system are reported. An electron channel with a high charge-carrier mobility (as high as 50000–60000 cm2/(V s)) is observed and studied for the first time in an isotype broken-gap p-GaInAsSb/ p-InAs heterostructure. The effects of electron-channel depletion and semimetal-semiconductor transition in the case of heavy doping of the quaternary alloy with acceptors are studied. Magnetotransport properties at temperatures of 4.2–200 K are studied in detail. Data on the energy spectrum and parameters of two-dimensional charge carriers at the heteroboundary are obtained. It is ascertained experimentally that, depending on the composition, either staggered (at x = 0.85) or broken-gap (at x = 0.95) heterojunctions can be formed in the Ga1− x InxAsySb1− y /GaSb, which is confirmed by theoretical calculations. The anomalous Hall effect and negative magnetoresistance were observed in GaInAsSb/InAs:Mn grown on substrates doped heavily with Mn magnetic acceptor impurity so that the hole concentration was as high as p > 5 × 1018 cm−3; these phenomena are caused by exchange interaction of Mn ions in InAs with high-mobility charge carriers in the electron channel at the heterointerface. [ABSTRACT FROM AUTHOR]

Specific features of the energy spectrum of a separated type-II heterojunction in an external magnetic field are studied theoretically and experimentally. It is shown that, due to hybridization of the states of the valence band of one semiconductor and the conduction band of the other semiconductor at the heterointerface, there are level anticrossings, which produce quasigaps in the density of states in a nonzero magnetic field. The experimental results of magnetotransport studies for the GaInAsSb/p-InAs quaternary solid solutions with different doping levels are shown to agree well with the results of simulation, and specific features of the energy spectrum of separated type-II heterojunctions are established. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Epitaxial layers of phosphorus-rich InAs[sub 1-y-x]Sb[sub y]P[sub x] solid solutions were obtained by liquid phase epitaxy (LPE). The films with x = 0.32 were grown at 575°C on isoperiodic (100)InAs substrates. It is shown that the growth of InAsSbP layers from a phosphorus-rich liquid phase is accompanied by saturation of the phosphorus content in the solid state. InAsSbP-based diode heterostructures emitting in the 2.6-2.8 µm wavelength range were obtained, the output emission power of which is sufficient for detecting both natural and industrial gases in the atmosphere. [ABSTRACT FROM AUTHOR]

Long-wavelength photodiodes based on LPE-grown type-II heterostructures in lattice-matched GaSb/InGaAsSb/GaInAsSb and GaSb/InGaAsSb/AlGaAsSb systems were fabricated and studied. Band energy diagram engineering for heterostructures with wide- and narrow-gap layers allows the photodiode parameters to be controlled by varying the conditions at heterointerfaces. Electrical and photoelectric characteristics and the dark current mechanisms in the heterostructures were investigated. The optimal photodiode structure was selected that consists of two type-II broken-gap heterojunctions and one p-n-junction in the nar- row-gap active layer. Room-temperature detectivity D[sup *, sub λ] = 4.1 × 10[sup 8] cm Hz[sup ½]/W at λ = 4.7 µm was obtained. Type-II heterostructures may help develop high-efficiency uncooled photodiodes for the 1.6-4.8 µm range for gas analysis, environmental monitoring, and also the diagnostics of combustion and explosion products. [ABSTRACT FROM AUTHOR]

Magnetotransport properties of the narrow-gap In[sub x]Ga[sub 1-x]As[sub y]Sb[sub 1-y]/GaSb heterojunctions grown by liquid-phase epitaxy with various In content in the solid solution (x=0.85-0.95 and E[sub g] ≤ 0.4 eV) were studied. It is shown that, depending on the In content in these heterostructures, type II staggered-lineup (x = 0.85) or brokengap heterojunctions (x = 0.95) with high mobility in the electron channel at the interface (µ ... 20 000 cm²/(V s)) can be realized. For x = 0.92, depending on temperature, both types of heterojunctions were observed. Obtained results are in good agreement with the band energy diagram of the type II InGaAsSb/GaSb heterostructures under study. [ABSTRACT FROM AUTHOR]

Current-tunable diode lasers with narrow emission lines for laser spectroscopy in the 3.2-3.4 µm wavelength range are developed. The lasers, based on an InAsSb/InAsSbP double heterostructure, have a widestripe cavity. The wave number increases from 3030 to 3034 cm[sup -1] as the current is raised from 1.5 to 3 times the threshold value at 70 K, while the full width at half-maximum of the laser line decreases from 18 to 10 MHz. It is demonstrated that the linewidth is determined by fluctuations of the cavity resonance frequencies as a result of fluctuations in the concentration of nonequilibrium charge carriers. [ABSTRACT FROM AUTHOR]

Magnetotransport properties of an electron channel at the heteroboundary in type II separated p-Ga[sub 1 - x]In[sub x]As[sub y]Sb[sub 1 - y]/p-InAs heterostructures grown by LPE (x = 0.09-0.22) were studied in the temperature range of 77-300 K. It is shown that an electron channel, which is formed at the heteroboundary and has high mobility µ = (3-5) x 10[sup 4] cm² V[sup -1] s[sup -1], exists throughout the whole composition range. The band diagram of the heterostructures under study is discussed, and some parameters of the electron channel are evaluated. It is found that the electron channel with high mobility persists up to room temperature. Type II GalnAsSb/p-InAs heterostructures can find application in new Hall sensor devices with an electron channel at the heteroboundary. [ABSTRACT FROM AUTHOR]

The results of a comparative study of the temperature dependence of the threshold current, the differential quantum efficiency, and the polarization of light are reported for type-I and type-II InAsSb/InAsSbP heterostructures and for a tunneling injection laser utilizing a type-II GalnAsSb/InGaAsSb separate-confinement heterojunction. The theoretically predicted suppression of nonradiative Auger recombination in type-II InAsSb/InAsSbP lasers with a large ratio of band discontinuities at the interface ΔE[sub v]/ΔE[sub c] = 3.4 is verified experimentally. Weakening of the temperature dependence of the threshold current is established for both type-II laser configurations. The maximum working temperatures T[sub lim] = 203 and 195 K and the characteristic temperatures T[sub 0] = 40 and 47 K are attained for (respectively) a conventional type-II InAsSb/InAsSbP laser and a type-II p-GaInAsSb/n-InGaAsSb tunneling injection laser. [ABSTRACT FROM AUTHOR]

Magnetotransport and the electron channel parameters are investigated in p-GaInAsSb/p-InAs heterojunctions as functions of the acceptor doping level of the quaternary (GaInAsSb) layer. An abrupt decrease in the carrier mobility with increased doping level in these heterojunctions is observed. This decrease can be attributed to the narrowing and depletion of the channel near the interface and strong localization of electrons in potential wells at the interface. [ABSTRACT FROM AUTHOR]

Galvanomagnetic phenomena and photoconductivity in broken-gap type-II GaInAsSb/p-InAs heterojunctions with different levels of doping of the solid solution with donor (Te) or acceptor (Zn) impurities have been investigated. It has been determined that in such structures an electronic channel, which determines the galvanomagnetic effects in a wide range of doping levels, is present at the heterojunction. A sharp decrease of the Hall mobility was observed in the experimental heterostructures with a high level of doping of the epitaxial layer with an acceptor impurity. The observed effect is due to exhaustion of the electronic channel as a result of carrier localization in potential wells at the heterojunction. [ABSTRACT FROM AUTHOR]

The diagrams of melt-solid solution (fusibility curves) and solid solution (I)-solid solution (II) (surfaces of spinodal decomposition of solid solutions) phase equilibria in the fivecomponent system In-Ga-As-Sb-P (the solid solutions are isoperiodic to the GaSb and InAs substrates) are calculated. The concentration ranges of the isovalent substitution solid solutions In[sub x]Ga[sub 1-x]As[sub y]Sb[sub z]P[sub 1 - y - z], which are accessible for synthesis by liquid-phase epitaxy, are calculated. [ABSTRACT FROM AUTHOR]

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[sup +]-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 (10[sup 6]-10[sup 7] cm[sup -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. [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]