Optical Gain Characteristics of Long-wavelength Type-II InGaAs/GaPAsSb Quantum Wells Grown on GaAs Substrates

The ptical gain characteristics of GaPAsSb/InGaAs quantum well (QW) structures are investigated using the multiband effective-mass theory. These results are also compared with those of type-II GaAsSb/GaAs QW structures. The optical gain is improved, and the peak wavelength is blueshifted with increasing GaP composition in the GaPAsSb well. The improvement in the optical gain can be explained by an increase in the optical matrix element. However, quasi-Fermi level separations slightly decrease with increasing GaP composition in the GaPAs layer. This is attributed to the fact that the conventional GaAsSb/InGaAs/GaAs structure shows a larger energy spacing between the first subband (HH1) and higher subbands in the valence band structure.