Increasing the optical transition oscillator strength in GaSb-based type II quantum wells

The oscillator strength of the fundamental optical transition in GaSb-based type II quantum well structures as one of the crucial parameters for the performance of interband cascade lasers was investigated. Modulation spectroscopy, supported by eight-band k·p calculations, has been employed as a sensitive probing technique allowing to determine the transition intensities of samples with various layer structures. The results show that altering the composition of the valence band well in a type II system can efficiently enhance the transition oscillator strength. Especially, the utilization of a quaternary GaInAsSb material for hole confinement turned out to be highly beneficial.