Losses in GaInAs(P)/InP and GaAlSb(As)/GaSb lasers - The influence of the split-off valence band

Abstract
GaInAs(P)/InP and GaAlSb(As)/GaSb are interesting material systems for long wavelength optical fiber communication. However lasers fabricated from these materials exhibit a substantially higher temperature dependence of the threshold current than GaAs/ GaAlAs lasers ("T 0 -problem"). lntervalence band absorption and CHSH-Auger-recombination have been suggested as two possible causes for the strong temperature dependent losses in long wavelength lasers. Both mechanisms, if present, should lead to a population of the split-off valence band. In GaInAsP/InP lasers, we have studied this population by directly observing the radiative high-energy recombination of electrons with holes in the split-off valence band. In the case of the band structure of GaAlSb(As), the band gap energy E 0 is close or equal to the spin-orbit splitting energy Δ 0 , which favors hole-Auger recombination and intervalence band absorption, as confirmed by our experimental results.