Design and modeling of InP-based InGaAs/GaAsSb type-II 'W' type quantum wells for mid-Infrared laser applications.

We have theoretically studied the InP based InGaAs/GaAsSb /InAlAs type-II 'W' quantum wells (QWs) using the eight band k.p theory. The trade-off between the emission wavelength and the magnitude of the transition matrix element was investigated with various structural parameters of the 'W' QWs. For the same emission wavelength, the devices with thinner InGaAs/GaAsSb layers and a higher Sb content in GaAsSb could provide higher transition strength. The gain spectra and their peak values at various carrier densities were calculated. We have also found that a more balanced electron and hole masses in the type-II 'W' QWs can benefit the material gain. In our designed cases, we have seen that the reduced hole effective mass due to a higher Sb content can partially compensate the gain loss caused by the reduced transition matrix element. Based on the optimized design, a material gain above 103 cm-1 is readily achievable for a single properly designed 'W' quantum well. [ABSTRACT FROM AUTHOR]