Summary Abstract: InGaAsSb/A1GaAsSb Double Heterostructure Laser Prepared by Molecular Beam Epitaxy

Semiconductor lasers emitting in the 2-4 um range are of considerable interest as sources for the next generation very low loss fiber communication systems. Flouride glass fibers currently under investigation are predicted to have minimum losses in the 2-4 um wavelength region which are more than one order of magnitude lower than the minimum losses at 1.55 um of the best silica fibers. The InGaAsSb alloys lattice-matched to GaSb substrate are of particular interest because their bandgaps correspond to wavelengths over a wide spectral range from 1.7 to 4.3 um. In addition, the A1GaAsSb alloys can be grown lattice-matched to GaSb as cladding layers to provide both electrical and optical confinements. There has been a considerable effort to study the epitaxial growth of these materials and to fabricate heterostructure lasers emitting near 2 um. Most of the previous results have been obtained using liquid phase epitaxy (LPE), which has encountered several problems, including dissolution of the substrate in the melt, difficulties in growing high A1 composition A1GaAsSb cladding layers and a large miscibility gap in most of the central portion of the quarternary phase diagram which prohibits the LPE growth of InGaAsSb with emission wavelength longer than -2.3 um.