1,721,116 research outputs found
Thermal characteristics of optical gain for GaInNAs quantum wells at 1.3 mu m
No full textThe gain characteristics of 1.3-mum-wavelength GaInNAs, InGaAlAs, and InGaAsP single-quantum-well structures are studied and compared. Among these quantum wells, GaInNAs offers the lowest carrier density over a wide range of temperature (300-400 K) for applications that require high gain because of the highest differential gain. It is due to the large electron effective mass originating from the nitrogen incorporation. The change in threshold carrier density with temperature is smallest for GaInNAs because of the large conduction band offset and the large differences in the band gap energy between the well and the barrier. The interaction with the temperature-independent nitrogen states makes the shift of gain with temperature slowest as well. For these reasons, the threshold current of GaInNAs is expected to be more temperature independent than those of other materials. (C) 2001 American Institute of Physics.The authors thank Jae-Heon Shin of ETRI and J. Hader
of the University of Arizona for informative discussions.
This work was supported by the National Research Laboratory
Project and ETRI
Design considerations of GaInNAs-GaAs quantum wells: Effects of indium and nitrogen mole fractions
No full textThe influences of In and N compositions on the optical gain characteristics of a GaInNAs-GaAs single quantum well are studied theoretically for the first time. When compared with GaInAs, GaInNAs shows a higher optical gain and a longer emission wavelength, under the condition of identical strain. For a given operating wavelength, the higher-In GaInNAs quantum well exhibits a larger optical gain and a smaller carrier leakage than the higher-N GaInNAs quantum well. For example, more than a two-fold improvement in threshold current is expected from the higher-In Ga0.6In0.4N0.01As0.99 quantum well laser than the higher-N Ga0.75In0.25N0.02As0.98 quantum well laser operating at 1.3 mu m
Effects of particle shape and size on the homogeneity of dispersed U3Si particles in high uranium density research reactor fuels
No full textIn order to improve the homogeneity of the distributed U3Si fuel particles in the Al matrix of a high density research reactor fuel, the effect of the U3Si particle shape and size on the homogeneity of research reactor fuels has been investigated. The homogeneity of the distributed U3Si fuel particles in the Al matrix was evaluated by the apparent density measurement method. The homogeneity of a mixture consisting of comminuted irregular shaped U3Si particles and Al powders is superior to that of a mixture consisting of atomized U3Si particles and Al powders. From the measurement of the repose angle of the U3Si particles, it was noted that the cohesive strength of comminuted U3Si particles is higher than that of atomized U3Si particles, The homogeneity of a mixture consisting of finely atomized U3Si particles and Al powders is higher than that of a mixture consisting of coarsely atomized U3Si particles and Al powders, This result indicates that the cohesive strength of fine U3Si particles is higher than that of coarse U3Si particles. The homogeneity of U3Si/Al nuclear reactor fuel is improved by the formation of the an adsorbed layers between the U3Si and the Al powders. (C) 2001 Published by Elsevier Science B.V
Effects of particle shape and size on the homogeneity of dispersed U3Si particles in high uranium density research reactor fuels
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