Aluminum-free strained-layer lasers emitting at 1.14 μm on low-composition InGaAs:n substrates by metalorganic chemical vapor deposition
Broad-area (W=150 /spl mu/m) single-quantum-well (SQW) lasers have been successfully fabricated on n-type In/sub 0.03/Ga/sub 0.97/As substrates without incorporating aluminum-containing alloys. The strained-layer InGaP-GaAs-InGaAs heterostructure was grown by atmospheric pressure metalorganic chemical vapor deposition. Due to both the increased substrate lattice constant and the partial strain compensation supplied by the tensile-strained GaAs optical guiding layers, a peak emission wavelength of 1.1403 /spl mu/m is obtained for a 1-mm cavity length.
Fabrication of In/sub 0.25/Ga/sub 0.75/As/InGaAsP strained SQW lasers on In/sub 0.05/Ga/sub 0.95/As ternary substrate
A uniform In/sub 0.05/Ga/sub 0.95/As ternary substrate was grown by using liquid encapsulated Czochralski (LEC) technique with a method of supplying GaAs source material at a constant temperature, and InGaAs/InGaAsP strained single quantum well (SQW) lasers were fabricated on the substrate for the first time. The lasers lased at 1.03 /spl mu/m and exhibited low threshold current density of 222 A/cm/sup 2/ and excellent characteristic temperature of 221 K, showing that the ternary substrate has a sufficient quality for laser fabrication.<<ETX>>
EFFECT OF SAMPLE PREPARATION ON WATER TREE RESISTANCE OF XLPE/SEBS BLENDS
The effects of an aromatic polymer, such as poly[styrene-b-(ethylene-co-butylene)b-styrene] (SEBS), and its preparation processes on water tree resistance, morphology, crystallinity, dielectric constant and dielectric loss tangent of crosslinked polyethylene (XLPE)/SEBS and XLPE/SEBS/ethylene vinyl acetate (EVA) blends were investigated. The XLPE/SEBS samples were characterized by means of differential scanning calorimetry, scanning electron microscopy, dielectric spectral analysis and the accelerated water treeing experiment. The results clearly showed that although SEBS was partially compatible with LDPE and it was dispersed evenly in XLPE matrix, the blends demonstrated excellent dielectric performances, such as dielectric constant and dissipation factor. The crystallinity of XLPE/SEBS blends was decreased with increase in SEBS content and it was further decreased with the addition of EVA. SEBS could effectively improve the water-tree resistance of XLPE and both SEBS and EVA were found to improve the water tree resistance of XLPE synergistically as expected. The differences in sample preparation processes could change the phase morphology and dielectric performance of the blends, and could also influence the dispersion of SEBS in XLPE matrix as well as the crystallinity of the blends. Different preparation processes led to different water tree resistance behaviours of the samples. The improvement of SEBS dispersion in XLPE matrix helped to improve the water tree resistance of XLPE.