InGaAs/GaAsSb/InP terahertz quantum cascade lasers

The development of In0.53Ga0.47As/GaAs0.51Sb0.49 terahertz quantum cascade lasers is reviewed, starting with the first demonstration, through growth direction dependent performance issues, to high performance devices. This InP-based material system is an attractive alternative to the almost exclusively used GaAs/AlxGa1-xAs. Devices achieve maximum operating temperatures of 142 K and exhibit broadband lasing over a range of 660 GHz. A special focus has to be put on the growth direction related interface asymmetry for this material system. Symmetric active region designs are an elegant technique to investigate such asymmetries. A significant impact on the device performance is observed and attributed to interface roughness scattering.