An approach to reduction of uncertainties in internal doses reconstructed for the Techa River population

A methodology was developed for reduction of uncertainties in estimates of internal dose for residents of the Techa Riverside communities, who were exposed as a result of releases of radionuclides from the Mayak plutonium production facility in 1949-56. The 'Techa River Dosimetry System' (TRDS) was specifically elaborated for reconstruction of doses. A preliminary analysis of uncertainty for doses estimated using the current version of the TRDS showed large ranges in the uncertainty of internal absorbed dose and led to suggestions of methods to reduce uncertainties. The new methodological approaches described in this paper will allow for significant reduction of uncertainties of 90Sr-dose. The major sources of reduction are: making use of individual measured values of 90Sr and through development of a Household Registry to associate unmeasured persons with measured persons living in the same household(s).     

Mode-Locked Lasers with “Thin” Quantum Wells in 1.55 μm Spectral Range

Technical Physics Letters - We present the results of an experimental study of two-section semiconductor lasers with active region consisting of three 3.1 nm InGaAs/InGaAlAs quantum wells. Passive...     

On the gain properties of “thin” elastically strained InGaAs/InGaAlAs quantum wells emitting in the near-infrared spectral region near 1550 nm

The results of experimental studies of the gain properties of “thin” (3.2 nm thick) elastically strained InGaAs/InGaAlAs quantum wells emitting in the near-infrared spectral region near 1550 nm are presented. The results of studying the threshold and gain characteristics of stripe laser diodes with active regions based on “thin” quantum wells with a lattice–substrate mismatch of +1.0% show that the quantum wells under study exhibit a high modal gain of 11 cm^–1 and a low transparency current density of 46 A/cm² per quantum well.     

Volume Gallium Oxide Crystals Grown from Melt by the Czochralski Method in an Oxygen-Containing Atmosphere

Technical Physics Letters - Results of successful experiments on the growth of gallium oxide (β-Ga2O3) crystals by the Czochralski method are reported. The influence of growth atmosphere on...     

Room Temperature Lasing of Multi-Stage Quantum-Cascade Lasers at 8 μm Wavelength

Semiconductors - Room-temperature lasing at a wavelength of 8 μm in multistage quantum-cascade lasers pumped by current pulses is demonstrated. A quantum-cascade laser heterostructure based on...     

The Influence of the Parameters of a Short-Period InGaAs/InGaAlAs Superlattice on Photoluminescence Efficiency

Technical Physics Letters - We have studied heterostructures based on short-period InGaAs/InGaAlAs superlattices (SLs) manufactured by molecular-beam epitaxy on InP substrates, intended for use as...     

Dislocations at the interface between sapphire and GaN

GaN layers grown by metal organic vapour phase epitaxy on sapphire were imaged by synchrotron radiation X-ray topography. The threading dislocations could not be resolved in the topographs due to their high density, but a smaller density of about 10⁵ cm⁻² defects were seen in the interface between GaN and sapphire by utilizing large-area back-reflection topography for the sapphire substrates. The misfit dislocation images in the topographs form a well-resolved cellular network, in which the average cell size is roughly 30 μm. Different cell shapes in the misfit dislocation networks are observed on different samples. Also, images of small-angle grains of similar size were found in transmission section topographs of the GaN layers.     

Electroluminescence of InAs/InAs(Sb)/InAsSbP LED heterostructures in the temperature range 4.2–300 K

The electroluminescence of InAs/InAsSbP and InAsSb/InAsSbP LED heterostructures grown on InAs substrates is studied in the temperature range T = 4.2–300 K. At low temperatures (T = 4.2–100 K), stimulated emission is observed for the InAs/InAsSbP and InAsSb/InAsSbP heterostructures with an optical cavity formed normal to the growth plane at wavelengths of, respectively, 3.03 and 3.55 μm. The emission becomes spontaneous at T > 70 K due to the resonant “switch-on” of the CHHS Auger recombination process in which the energy of a recombining electron–hole pair is transferred to a hole, with hole transition to the spin–orbit-split band. It remains spontaneous up to room temperature because of the influence exerted by other Auger processes. The results obtained show that InAs/InAs(Sb)/InAsSbP structures are promising for the fabrication of vertically emitting mid-IR lasers.     

High-Power Quantum-Cascade Lasers Emitting in the 8-μm Wavelength Range

Technical Physics Letters - Molecular beam epitaxy techniques were used to grow a quantum-cascade laser (QCL) heterostructure based on an In0.53Ga0.47As/Al0.48In0.52As heteropair lattice-matched...