An automated system based on cryogenic probe station for integrated studies of semiconductor light-emitting structures and wafers in the range of 15 to 475 K

An automated system for integrated electrophysical and optical studies of semiconductor nanoheterostructures, which operates in a wide temperature range from 15 to 475 K, is designed. The setup is intended to measure the temperature and frequency admittance and electroluminescence spectra of light-emitting diode and laser chips formed on substrates of diameter up to 50.2 mm, and the distribution of parameters over the wafer. The setup includes the closed-cycle helium cryogenic station, LCR meter, and temperature controller. The characterization results of nanoheterostructures with InGaN/GaN multiple quantum wells, which are used for creating highly efficient white and blue light-emitting diodes, are presented.     

High-efficiency LEDs of 1.6–2.4 µm spectral range for medical diagnostics and environment monitoring

High efficient LED structures covering the spectral range of 1.6–2.4 μm have been developed on the basis of GaSb and its solid solutions. The electroluminescent characteristics and their temperature and current dependences have been studied. The radiative and nonradiative recombination mechanisms and their effect on the quantum efficiency have been investigated. A quantum efficiency of 40–60% has been obtained in the quasi-steady mode at room temperature. A short-pulse optical power of 170 mW was reached. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 37, No. 8, 2003, pp. 996–1009. Original Russian Text Copyright ? 2003 by Stoyanov, Zhurtanov, Astakhova, Imenkov, Yakovlev.     

Spectral and mode characteristics of InAsSbP/InAsSb/InAsSbP lasers in the spectral region near 3.3 µm

The characteristic features of the continuous-wave lasing spectra near 3.3 μm of multimode InAsSbP/InAsSb/InAsSbP double-heterostructure diode lasers are shown. The observation of mode switching to longer and shorter wavelengths at cryogenic temperatures is reported. It is shown that suppression of the longitudinal side modes closest to the main mode results in large mode jumps in energy during mode tuning by current. The characteristics which were observed are explained by gain spectrum inhomogeneity due to spectral hole burning in narrow-gap semiconductors. The intraband charge-carrier relaxation times in the active region are estimated. Fiz. Tekh. Poluprovodn. 39, 1139–1144 (September 1998)     

Use of liquid sealants to protect still-waste-containing tanks-settling basins from corrosion

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 10, pp. 29–31, October, 1992.     

Memory of Distributed Computer Systems: Distinctive Features of Their Architectural-Structural Organization and Use

Distinctive features of architectural-structural organization and use of memory networks are considered with the aim of choosing an optimal configuration in designing distributed computer systems.     

Preparation of structurally-colored aromatic polyamides and their physicochemical properties

Conclusions One-, two-, and three-stage methods of preparing structurally-dyed aromatic polyamides with chromophoric fragments in the chain have been investigated.It has been shown that the molecular weight of the polymers obtained and the proportion of chromophores bound into their chain is determined by the reactivity of the starting diaminoanthraquinones.It has been found that the introduction of anthraquinone units into the poly-m-phenylene isophthalamide chain has little effect on the structure or basic physicochemical properties of the polyamide, but gives the polymer a uniform and regular coloration.Structural dyeing of poly-m-phenylene isophthalamide with fragments of 1,5-DAAQ or 4,8-DADHAQ increases the resistance of the polyamide fibres to UV irradiation.The authors express their thanks to Yu. Ya. Shavarin and N. M. Bol'bit for performance of the fibre irradiation, and also to B. A. Tsaplin for thermomechanical testing of the fibres.L. Ya. Karpov NIFKhI, Moscow. VNIISV, Tver'. Translated from Khimicheskie Volokna, No. 2, pp. 24–27, March–April, 1992.