GaAsSb/GaAs type-II quantum well and its application on /spl sim/1.3 /spl mu/m laser

The band offset of the type-II GaAs/sub 0.7/Sb/sub 0.3//GaAs quantum well (QW) is studied. We propose an extrapolation method to remove the band-bending effect and determine the flat-band transition energy of the type-II QW from photoluminescence (PL) measurement. Then, we compare the PL peak energies of the type-II GaAs/sub 0.7/Sb/sub 0.3//GaAs QW and the type-I Al/sub 0.3/Ga/sub 0.7/As/GaAs/sub 0.7/Sb/sub 0.3/ QW to obtain the strained band gap energy of GaAs/sub 0.7/Sb/sub 0.3/ and the valence-band-offset ratio of the type-II QW. The obtained band gap energy and valence-band-offset ratio are 1.01 eV and 1.15. GaAsSb/GaAs double-quantum-well lasers were also grown and fabricated. The laser demonstrates a very low threshold current density of 210 A/cm/sup 2/ with an emission wavelength of 1.28 /spl mu/m.