IMPROVED PERFORMANCE OF LONG-WAVELENGTH STRAINED BULK-LIKE SEMICONDUCTOR-LASERS

We show that the incorporation of either tensile or compressive strain can have significant advantages for long wavelength bulk-like lasers, with greater advantage being achieved in tensile-strained structures. The application of biaxial tension to the active region of a bulk or quantum-well III-V semiconductor laser can significantly enhance TM gain compared to TE gain and reduce the threshold current density, due to improved suppression of spontaneous emission polarized in the growth plane of the laser structure. The differential gain is enhanced compared to unstrained structures and a larger peak gain can be achieved than in comparable structures under biaxial compression. We calculate the effect of the spin-orbit interaction on the polarized gain and character of the valence states as a function of built-in strain. We include the spin-split-off band in our calculations and show that the strain-induced interaction with this band has a significant influence on laser characteristics, particularly in tensile-strained structures, where it further enhances the TM gain over the TE gain. Finally, we investigate the effect of biaxial strain on the major intrinsic loss mechanism of Auger recombination in long wavelength 1.55 mum lasers. We observe a rapid increase in the Auger threshold activation energies, leading to a reduction in the Auger rates, for moderate tensile and compressive strain, compared to an unstrained structure.