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The article presents a new design of an AlGaAs/GaAs low-voltage thyristor for efficient high-current pulse generation at high repetition rates. It is demonstrated that optimizing the low-voltage thyristor p-base doping profile by using a thin highly doped layer allows for a significant increase in the operating frequencies. This applies to both a thyristor working without an external load and a vertical stack of a thyristor with a laser diode mini bar (LDMB). It is shown that the use of a 0.1- $\mu \text{m}$ -thick highly doped layer, formed at the side of the p-base close to the n-emitter, leads to a significant increase of the holding current, which in our case exceeds 70 mA. At the same time, we were still able to obtain a low residual voltage of 1.5 V and a high blocking voltage of 32 V. The developed low-voltage thyristors have demonstrated the possibility of generating current pulses of 30-ns duration at a repetition rate of 10/70 kHz with an amplitude of 125/110 A, as well as the efficient pumping of LDMBs and laser pulses with a peak power of 68/57.5 W, respectively.

The spatial and temporal dynamics of the optical loss and carrier density in the heterostructure of a semiconductor laser with a segmented contact are studied using an optical pump–probe technique based on the injection of probe radiation with a wavelength of 1560 nm into a semiconductor laser chip under study that is based on an AlGaAs/InGaAs/GaAs heterostructure and emits at wavelength of 1010 nm. It is demonstrated that employing probe light at a wavelength of 1560 nm enables sensitivity in measuring an internal optical loss of no less than 1 cm–1. The segmented design of the current pumping region made it possible to estimate the absolute internal optical loss. It is shown that changing the configuration of the Fabry–Perot eigenmodes of the laser affects the carrier distribution and the internal optical loss both in the current pumping region and in the passive, current unpumped part of the laser chip.

The emission characteristics of narrow mesa-stripe (5.5 μm) lasers based on asymmetric AlGaAs/GaAs heterostructures are studied. It is shown that the maximum optical power achieved in the continuous-wave (CW) operation mode is limited by heating and reaches a value of 1695 mW at a current of 2350 mA at +25°C, with the maximum efficiency reaching 54.8%. Reducing the working temperature to –8°C makes it possible to raise the maximum low-mode CW power to 2 W. A peak power of 2930 mW is obtained under pumping with current pulses (width 240 ns, amplitude 4230 mA). It is shown that the power profile has in the pulsed mode an “optical dip” region in which low-efficiency lasing occurs with the generation of a train of subnanosecond pulses.

Near field dynamics of a single-mode laser diode (λ= 1060 nm) based on InGaAs/AlGaAs/GaAs is studied. A narrow-stripe laser diode with a straight ridge of 5.1-µm width having no distributed feedback elements demonstrates a constructive and destructive interference in opposite parts from the centre of the near field at the same time. The temporal behavior of an optical power at different points of the near field is studied. It is shown there is a domain in the optical pulse at a current corresponding to the "kink" region when two modes interfere destructively on one side of the near field in the lateral direction from the center of the stripe, and constructively they interfere on another side.

Studies of multimode and single-mode semiconductor lasers with a surface distributed Bragg reflector (S-DBR) were carried out. S-DBR with a period of 2 μm was formed in the upper cladding layer by contact photolithography. The spectrum width for all laser designs did not exceed 0.3 nm both at continuous wave (CW) and pulse of 100 ns pump. Temperature stability of emission wavelength increase from a value of 0.35 nm/°С for a Fabry-Perot laser to a value of 0.075 nm/°С for a S-DBR laser was demonstrated. The relatively low output optical power of high-order S-DBR lasers is associated with the presence of diffraction modes emitting from the surface of the DBR.

Pulse-pumped MOVPE-fabricated (metal-organic vapor-phase epitaxy) semiconductor lasers emitting in the spectral ranges 1000–1100 and 1400–1600 nm at temperatures of 110–120 K are studied. It is found that cooling the lasers for both spectral ranges to low temperature results in their light–current curves approaching linearity, and an optical power of, respectively, 110 and 20 W can be attained. The low-temperature effect is reduced for lasers emitting in the spectral range 1400–1600 nm. The processes affecting a rise in the internal optical loss in semiconductor lasers are considered. It is shown that an increase in the carrier concentration in the waveguide of a laser structure greatly depends on temperature and is determined by the noninstantaneous capture (capture rate) of carriers from the waveguide into the active region. It is demonstrated that, upon lowering the temperature to 115K, the concentration of electrons and holes in the waveguide becomes lower, which leads to a significant decrease in the internal optical loss and to an increase in the output optical power of the semiconductor laser.

Objective: to evaluate the impact of anemia in pregnant women on the formation of an early neonatal adaptation period. The investigation enrolled 84 mother-baby pairs followed up at a Krasnoyarsk maternity hospital. Group 1 consisted of 40 infants born to pregnant women with grade 1 anemia; Group 2 included 19 babies born to mothers with grade 2 anemia. A control group comprised 25 babies born to somatically healthy non-anemic pregnant women. The incidence of transient conditions, signs of physiological immaturity, as well as changes in motor activity and tendon reflexes was significantly higher in the infants whose mothers were anemic during pregnancy. It is concluded that anemia in pregnant women has a considerable impact on neonatal health. These children have more commonly hemorrhagic-ischemic CNS disorders, which may lead to further psychomotor and speech retarded.

We report an experimental study of power characteristics of semiconductor lasers based on MOVPE-grown asymmetric separate-confinement heterostructures with a broadened waveguide as functions of cavity length, stripe contact width and mirror reflectivities. It is shown that at high current pump levels, the variation of the cavity parameters of a semiconductor laser (width, length and mirror reflectivities) influences the light – current (L – I) characteristic saturation and maximum optical power by affecting such laser characteristics, as the current density and the optical output loss. A model is elaborated and an optical power of semiconductor lasers is calculated by taking into account the dependence of the internal optical loss on pump current density and concentration distribution of charge carriers and photons along the cavity axis of the cavity. It is found that only introduction of the dependence of the internal optical loss on pump current density to the calculation model provides a good agreement between experimental and calculated L – I characteristics for all scenarios of variations in the laser cavity parameters.

Semiconductor lasers based on MOVPE-grown asymmetric separate-confinement heterostructures with a broadened waveguide and emitting in the wavelength range 1.0 – 1.1 μm are studied. It is found that the intensity of spontaneous emission from the active region increases with increasing pump current above the lasing threshold and that this is caused by a growth in the concentration of charge carriers in the active region due to the modal gain enhancement needed to compensate for the growing internal optical loss at high pulsed pump currents. It is shown that the increase in the internal optical loss with increasing pulsed pump current is one of the main reasons for saturation of the light – current characteristics of high-power semiconductor lasers.

Approaches to the development of laser heterostructures with a broadened single-mode waveguide are studied theoretically and experimentally. It is shown that the use of n- and p-type emitters with different refractive-index values ensures lasing in the fundamental mode only, if the thickness of the waveguide layer is 2 μm. The studied semiconductor lasers fabricated using the developed heterostructure feature internal optical losses amounting to 0.6 cm−1; the divergence in the plane perpendicular to the p-n junction is 23°. In the continuous lasing mode at room temperature, a linear power-current characteristic is obtained at an output optical power as high as 7 W.

Laser heterostructures with waveguides and emitter layers made of AlGaAs and AlGaAsP alloys are grown by hydride metal-organic vapor-phase epitaxy on a GaAs substrate and studied. It was shown that the heterostructure containing AlGaAsP layers has a large curvature radius in comparison with the structure consisting of AlGaAs layers. Ridge waveguide lasers with an aperture of 100 μm are fabricated based on the AlGaAsP/GaAs laser heterostructure and studied. The internal optical loss of the lasers is 0.75 cm−1; the characteristic parameter T0 = 140 K in the temperature range of 20–70°C. The maximum optical output power per mirror reached 4.1 W; cw lasing was retained at a heat sink temperature of 120°C.

Heterostructures with an active region containing a Ga0.59In0.41As quantum well located between GaAs1 − y P y compensating layers were studied using photoluminescence spectroscopy. It was shown that an increase in the phosphorus content in compensating layers makes it possible to obtain unrelaxed heterostructures with wider Ga0.59In0.41As quantum wells. On the basis of photoluminescence studies, the parameters of such a composite active region were chosen with a view to attaining the longest lasing wavelength possible. Laser heterostructures with a composite active region consisting of a highly strained Ga0.59In0.41As quantum well located between GaAs0.85P0.15 compensating layers were grown on GaAs substrates by metalloorganic chemical vapor deposition. Stripe mesa-structure laser diodes of 100-μm aperture emitting at 1220 nm were fabricated. The highest emission power of these laser diodes in the continuous-wave regime amounted to 2 W per output mirror.

The basic technical characteristics of the navigation device, realized on the basis of a strapdown inertial unit, satellite navigation equipment, and a computing device of a new generation on the basis of the “Malakhit-7” digital computing system are described. Preliminary estimates of operational and precision characteristics of the navigation device components with the use of the corresponding mathematical model and a number of test benches of the Federal State Unitary Enterprise (FSUE) “Scientific and Production Association of Automatics” (`SPA of Automatics') are received.

Optical and electrical characteristics of different high-power multimode laser diodes with an emission wavelength of 835 nm are compared; the diodes were obtained on the basis of three systems of solid solutions: AlGaAS/GaAs, AlGaAs/GaAsP, and (Al)GaInP/GaInAsP. An output continuous optical power of 5 W is attained in lasers with a stripe width of 80 μm irrespective of the chosen material system. The highest optical power, 7 W, is attained in the lasers based on the (Al)GaInP/GaInAsP system.

The parameters of high-power multimode laser diodes featuring a radiation wavelength of 808 nm obtained on the basis of asymmetric heterostructures with an ultrawide waveguide in the systems of AlGaAs/GaAs and (Al)GaInP/GaInAsP/GaAs are compared. In the lasers based on an AlGaAs/GaAs system, the maximum optical power was limited by optical degradation of the SiO2/Si mirrors and amounted to 4.7 W. In the lasers based on an (Al)GaInP/GaInAsP/GaAs system, the maximum optical power was limited by thermal saturation and equaled 7 W. The obtained results show that the (Al)GaInP/GaInAsP/GaAs system is more reliable from the standpoint of an increase in both the maximum optical power and operation life of lasers.

Spectral and emission-power characteristics of semiconductor lasers based on quantum-dimensional asymmetric heterostructures with separate confinement in a system of InGaAs/GaAs/AlGaAs alloys are studied in the case of high pump levels in the pulsed mode of lasing (200 A, 100 ns, and 10 kHz). It is shown that, in lasers with a quantum-dimensional active region containing one or two levels of dimensional quantization, the spectrum consists of one or two lasing bands. It is established that the condition for inverse population of the second electron level and two-band lasing are attained due to leveling-off of the rate of stimulated recombination from the first electron level and a high density of states for the second level. It is shown that, in lasers with double-band lasing spectrum, the total emission spectrum exceeds appreciably the emission power of a laser with a single electron level and a single spectral band.

Spectral and light-current characteristics of separate-confinement lasers that are based on InAl-GaAs/InP and InGaAsP/InP alloys and emit in the wavelength range of 1.5–1.8 μm are studied at high excitation levels (up to 80 kA/cm2) in pulse operation (100 ns, 10 kHz). It is shown that the peak intensity in the stimulated-emission spectrum saturates as the pump current is increased. Further increase in the emitted power is attained owing to the emission-spectrum broadening to shorter wavelengths, similar to lasers on the GaAs substrates (λ = 1.04 μm). It is established experimentally that the broadening of the stimulated-emission spectrum to shorter wavelengths is caused by an increase in the threshold current and by an increase in the charge-carrier concentration in the active region. This concentration increases by a factor of 6–7 beyond the lasing threshold and can be as high as 1019 cm−3 in pulse operation. It is shown that saturation of the light-current characteristics in pulse operation takes place in the InAlGaAs/InP and InGaAsP/InP lasers as the pump current is increased. It is shown experimentally that there is a correlation between saturation of the light-current characteristic and an increase in the threshold current in the active region. An increase in the charge-carrier concentration and gradual filling of the active region and waveguide layers with electrons are observed as the pump current is increased; stimulated emission from the waveguide is observed at high pump currents.

We suggested and experimentally confirmed the effective method of internal optical loss reduction by high order mode suppression in a separate confinement quantum well laser heterostructure with asymmetric ultra thick waveguide. Manufacturing of InGaAs/GaAs/AlGaAs laser heterostructure with a 1.7 microm-thick asymmetric waveguide allowed attaining super low value of internal optical loss alphai=0.34 cm-1 preserving high efficiency and fundamental transverse mode operation. Record-high 16 W continuous wave (CW) and 145 W pulse room temperature front facet output optical power and 74% wallplug efficiency were attained in 100-microm-aperture 1.06-microm-emitting laser diodes with 3 mm cavity length.

The experiments on negative hydrogen ion beam production in a multi-aperture long-pulse surface-plasma source are described. H- ions are produced on the surface of a plasma grid covered by cesium and illuminated by fast plasma particles. The source uses a radio-frequency driver to generate plasma. A composite magnet system made of external permanent magnets confines and filters electrons in the plasma region, and deflects them in the extraction area. A multiaperture, multi-electrode ion optical system is used for beam formation. The electrode heating and cooling during long pulses is accomplished by circulating a heat transfer fluid through channels drilled in the electrodes bodies. H- ions extraction through a single aperture and 21 apertures was performed and studied. A stable H- beam with the current up to 0.7 A, energy up to 74 kV, and pulse duration up to 7 s was routinely obtained

High-power semiconductor lasers based on asymmetric quantum-dimensional separate confinement InGaAs/GaAs heterostructures with ultrathick waveguides were fabricated by means of metalorganic hydride vapor phase epitaxy technology. The laser characteristics were studied in a pulsed pumping regime, in which the emission was excited by current pulses of 100 ns duration at a repetition frequency of 10 kHz and an amplitude of up to 200 A. The passage to a pulsed lasing regime allowed the active region heating to be reduced and the output power to be increased to 145 W for a laser diode with a 100-μm exit aperture. The results obtained for the pulsed lasing regime show that saturation of the output power-current characteristic observed in the continuous-wave regime is fully determined by overheating of the active region of a semiconductor laser.

Asymmetric GaInAs/GaInAsP/AlGaAs heterostructures with the emission wavelength of 940 and 980 nm were grown by MOCVD. The composition of solid solution in the waveguide layer, Ga0.74In0.26As0.47P0.53, was chosen based on the calculations of the escape energy of electrons from the quantum well of the active region into the waveguide. Semiconductor lasers with the emission aperture of 100 μm were fabricated from these heterostructures. The CW output optical power of 12 W was achieved at room temperature. The internal optical loss was 0.6 and 0.3 cm−1 for 940 and 980 nm wavelengths, respectively.

Based on the results of model calculations and the data of photoluminescence measurements and transmission electron microscopy, the optimum composition (GaAs0.85P0.15) of compensating barriers for a structure with four highly strained Ga0.76In0.24 As quantum wells (QWs) has been established that excludes the relaxation of elastic stresses in these QWs. Laser heterostructures with four such QWs separated by said compensating barriers have been grown by means of hydride metalorganic chemical vapor deposition. Laser diodes with short (∼100 μm) resonators based on these heterostructures operate at λ = 1060 nm with an output radiation power of 100 mW in the continuous regime.

Asymmetric separate-confinement laser heterostructures with ultrawide waveguides based on AlGaAs/GaAs/InGaAs solid solutions, with an emission wavelength of ∼1080 nm, are grown by MOCVD. The optical and electrical properties of mesa-stripe lasers with a stripe width of ∼100 μm are studied. Lasers based on asymmetric heterostructures with ultrawide (>1 μm) waveguides demonstrate lasing in the fundamental transverse mode with an internal optical loss of as low as 0.34 cm−1. In laser diodes with a cavity length of more than 3 mm, the thermal resistance is reduced to 2°C/W, and the characteristic temperature T 0= 10°C is obtained in the range 0–100°C. A record-breaking wallplug efficiency of 74% and an output optical power of 16 W are reached in CW mode. Mean-time-between-failures testing for 1000 h at 65°C with an operation power of 3–4 W results in the power decreasing by 3–7%.

Metal-organic chemical vapor deposition (MOCVD) was used to form laser heterostructures in the system of GaInAsP/GaInP/AlGaInP solid solutions. The design of the laser structure was chosen on the basis of the calculated band offsets at the heteroboundaries in the active region of the waveguide. A maximal optical power of 320 mW is attained at the output of the mesa-stripe diode laser with a stripe width of W=5 µm in continuous-wave mode at 780 nm.

Optical and structural properties of InGaAsP solid solutions grown by MOVPE at 600°C on GaAs(001) substrates are studied. The photoluminescence spectra of InGaAsP solid solutions with a composition corresponding to the miscibility gap contain a main band and an additional auxiliary band. It is established that both bands are related to band-to-band radiative transitions; i. e., the studied layer includes two solid solutions with different compositions and different band gaps. It is shown that the observed high-energy shift of the additional band with an increasing level of excitation is governed by the nanometer size of domains in the corresponding solid solution. This conclusion is consistent with the results of TEM study, which revealed the presence of a periodic structure comprised of alternating domains with different compositions. This structure of alternating domains extends along the [100] and [010] directions with a characteristic period of 10 nm.

Carbon doping of GaAs and AlGaAs layers grown by low-pressure metalorganic chemical vapor deposition, using triethylgallium, trimethylaluminum and arsine as growth precursors and carbon tetrachloride as dopant precursor, were investigated. Doping level dependence on growth temperature, growth rate, V/III ratio and AlAs mole fraction was established. InGaAs/AlGaAs DQW broad waveguide separate confinement laser heterostructures with different p-clad doping have been studied. Heterostructures design and optimization of active area growth conditions have been fulfilled to obtain high-power operation of laser diodes (LDs) with low transverse divergence. Carbon tetrachloride and diethylzinc were used as p-type dopant precursors. There were investigated three types of heterostructures: (a) C-doped AlGaAs p-clad and heavy C-doped GaAs contact layer, (b) C-doped AlGaAs p-clad and heavy Zn-doped GaAs contact layer, (c) Zn-doped AlGaAs p-clad and heavy Zn-doped GaAs contact layer. Broad area LDs were manufactured and analyzed. As a result the optimal p-type dopant precursor for high-power LDs was discussed.

A metal-organic chemical vapor deposition (MOCVD) technique is developed for a diode laser heterostructure in a system of InGaAs/GaAs/AlGaAs solid solutions; the optimal sizes and the doping profile of the structure are determined to minimize the internal optical losses. Mesa-strip diode lasers with a threshold density of current Jth=150–200 A/cm2, internal optical loss factor αi=1.6–1.9 cm−1, and an internal quantum yield ηi=85–95% were fabricated. In the continuous lasing mode of a diode laser with a 100-µm-wide aperture and a wavelength of 0.98 µm, the optical power output was as high as 6.5 W and was limited by the catastrophic optical degradation of mirrors. The radiation divergence in the plane normal to the p-n junction amounts to θ⊥. The use of wide-gap waveguide layers, which deepens the potential electron well in the active region, is shown to reduce the temperature sensitivity of the InGaAs/GaAs/AlGaAs laser heterostructures in the temperature range from 0 to 70°C.

A MOCVD technology for growth of InGaAs/GaAs/InGaP laser heterostructures on a modified Epiquip VP-50-RP installation was developed. Mesa stripe laser diodes with threshold current density Jth=100–200 A/cm2, internal optical loss αi=1.3–1.7 cm−1, and internal quantum efficiency ηi=60–70% have been fabricated. A CW output optical power of 5 W has been obtained for a single 100-µm-wide aperture mesa stripe laser diode emitting at 1.03 µm. It is shown that use of AlGaAs waveguide layers, which increase the conduction band barrier offset, lowers the temperature sensitivity of laser heterostructures within the temperature range 10–80°C.

Continuous-wave output powers of 9.2 W at a constant heatsink temperature of 10°C and 12.2 W at a stabilized temperature of the active region have been obtained on an InGaAs/AlGaAs laser with a 0.4-µm-thick waveguide, operating at 1.03 µm. Record-breaking output mirror power densities of, respectively, 29.9 and 40 MW/cm2 have been achieved without catastrophic optical mirror damage in the two temperature-stabilization regimes. A maximum power conversion efficiency of 66% has been achieved in a laser with a cavity length of 2 mm.

Photoluminescence and electroluminescence techniques were used to study spontaneously forming periodic InGaAsP structures that consisted of two types of alternating solid-solution domains differing in composition and lattice constant. It was found experimentally that the volume of the narrow-gap material domains is smaller than that of the wide-gap domains. Existence of the inelastic strain caused by the large (2–3%) lattice constant mismatch between the adjacent domains was inferred. Laser diodes with the spontaneously forming periodic InGaAsP structures in the active region were fabricated, and lasing in the long-wavelength electroluminescence spectral band that originated from the radiative recombination in the narrow-gap domains was obtained. Lasing at the threshold current densities of 70 A/cm2 at 77 K and 700 A/cm2 at 300 K was observed in the highest-quality samples.

Arrays of strained nanoscale InP islands in an In0.49Ga0.51P host on a GaAs(100) substrate and InAs islands in a In0.53Ga0.47As host on an InP(100) substrate are obtained by metalorganic vapor-phase epitaxy (MOVPE). Their structural and photoluminescence properties are investigated. It is shown that the nanoscale islands that are formed measure 80 nm (InP/InGaP) and 25–60 nm (InAs/InGaAs). The photoluminescence spectra of the nanoscale islands display bands in the wavelength ranges 0.66–0.72 and 1.66–1.91 µm at 77 K with maxima whose position does not vary as the effective thickness of InP and InAs increases. The radiation efficiency of the nanoscale InP islands is two orders of magnitude greater than the luminescence intensity of the InAs islands.

Low-divergent, quasi-stationary neutral beams are often applied in modern magnetic fusion devices as a diagnostic tool providing unique information about plasma parameters. The most important requirements to these beams are sufficiently large current and energy of the particles, so that the beam could penetrate to plasma core. At the same time, duration of the beams should be long enough, close to that of a plasma shot, amounting to, at least, a few seconds for large machines. We developed neutral beam injector which is capable to meet above mentioned requirements. Plasma emitter in the injector is provided alternatively radio frequency or arc discharge in hydrogen (deuterium).

This paper discusses the photoluminescence and x-ray microstructural properties of epitaxial layers of solid solutions of InGaAsP isoperiodic with InP (100) and GaAs (100) substrates, obtained in the region of immiscibility and spinodal decay. It shows that there is good agreement of the experimental results with the theoretical model of spinodal decay. The boundaries of the region in which two solid phases of different composition exist in epitaxial layers of solid solutions of InGaAsP isoperiodic with the InP and GaAs substrates are determined. A periodic nanoheterostructure is obtained in an epitaxial layer of InGaAsP solid solutions with a repetition period of 650±30 A in two mutually perpendicular directions.

Heterostructures comprising highly strained GaAs quantum wells in Al0.48In0.52As and Ga0.47In0.53As layers have been grown by the metalorganic chemical vapor deposition method on InP(100) substrates. The photoluminescence spectra of these structures have been studied, and it is established that GaAs quantum wells form type-I heterojunctions with Al0.48In0.52As layers and type-II heterojunctions with Ga0.47In0.53As layers.

We have studied the photoluminescence of heterostructures based on solid solution systems of the GaInP/GaAsP/GaInAsP type grown by metalorganic chemical vapor deposition method. It is established that GaAs0.77P0.23 and Ga0.74In0.26As0.53P0.47 solid solutions form a type-II heterojunction. The conduction band offset at the GaAs0.77P0.23/Ga0.74In0.26As0.53P0.47 heteroboundary amounts to 90 meV, which makes the quaternary solid solution a preferred material for the active region of a laser heterostructure operating at λ=780 nm.

Results of photoluminescence (PL) studies of self-organized nanoscale InP islands (quantum dots, QDs) in the In0.49Ga0.51P matrix, grown on a GaAs substrate by metalorganic vapor phase epitaxy (MOVPE), are presented. Dependences of the PL efficiency on temperature in the range 77–300 K and on excitation level at pumping power densities of 0.01–5 kW/cm2 have been obtained. The PL spectra are a superposition of emission peaks from QDs and the wetting layer. Their intensity ratio depends on the pumping power and temperature, and the emission wavelength varies in the range 0.65–0.73 µm. At 77 K and low excitation level, InP QDs exhibit high temperature stability of the emission wavelength and high quantum efficiency.

In severe concomitant injury, there is evidently activated formation of free radicals with a further increase in the rate of lipid per-oxidation and with simultaneous depletion of antioxidant system activity. The administration of the traditional doses of antioxi-dants is ineffective. Higher-dose antioxidant therapy and use of novel agents can cause a considerable reduction in the rate of free radical processes and improve the results of treatment. Key words: oxidative stress, lipid peroxidation, antioxidants, lactoferrin.

Results are presented of investigations of the growth of self-organizing nanosize InP and InAsP clusters in an In0.5Ga0.5P matrix. The structure was characterized by low-temperature photoluminescence and transmission electron microscopy. The photoluminescence measurements revealed highly efficient radiative recombination from the quantum dots and indicated that the structures were of good optical quality. The average density and size of the InP clusters, determined from the results of the transmission electron microscope measurements, are 3×109 cm−2 and 80 nm, respectively.

Development of submonolayer deposition technique can offer significant flexibility in creation of strained heterostructures of different types and material systems. It was found that under certain growth conditions the deposition of InAs insertions of less than 1 monolayer (ML) thickness in GaAs matrix forms so-called sub-monolayer quantum dots (SML QDs). The energy spectrum of these QDs can be varied over a wide range by tuning the InAs coverage and the thickness of GaAs spacers. Stranski-Krastanow (In,Ga)As QDs (SK QDs), which have been investigated in more details, have proved theoretically predicted lower threshold current density of 26 A/cm2 in compare with QW lasers. However, strong size variation of SK QDs in combination with the relatively low sheet density leads to low peak gain achievable in the ground state. This problem is the reason of typically low efficiency of SK QD-based lasers. Due to higher gain, SML QDs have proved their potential for high power laser application. In this presentation we report on further progress in the technology of SML QD lasers demonstrating high output power (6W) from 100-μm-wide laser diode emitting at 0.94 μm. High power QW-based lasers of the state-of-the-art performance are also presented for comparison.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

To provide basic operations of semiconductor and radiation materials technologies, a multipurpose implanter with intense ion beams was developed at the Institute of Nuclear Physics. The generated beamparameters are as follows: ions are H+, O+; C+; the ion energy is up to 200 keV; the beam current is up to 2 mA; and the implantation mode is continuous. The size of the target to be processed can reach 76 × 76 mm2. During the implanter operation, the target chamber vacuum reaches 10−4 Pa. The entire process of target irradiation is fully automated.

An investigation was made of the possibility of using reduced-pressure MOC hydride epitaxy to fabricate highly strained (compressive stress) InxGa1−xAs/In0.53Ga0.47As quantum wells on indium phosphide (100) substrates. The photoluminescence properties of these heterostructures were investigated. It was shown that these heterostructures are potentially useful for laser diodes emitting in the 1.5–2 μm range, which is important for environmental monitoring.

Measurements are conducted of the Kerr constant of ultrapure water with resistivity 107 Ω · cm. Values of the Kerr constant of (3.26 ± 0.10) · 10-7 and (2.29 ± 0.07) · 10-7 esu were obtained at a temperature of 30 °C for wavelengths of 441.6 nm and 632.8 nm.