Investigation of injector doping density on intersubband terahertz electro-luminescence from GaAs–AlGaAs quantum cascade structures

We report a comprehensive study of GaAs–Al0.15Ga0.85As quantum cascade electro-luminescence devices designed to emit in the far-infrared. Strong intersubband electro-luminescence is observed at View the MathML source with a FWHM of typically View the MathML source. We investigate the intersubband emission as a function of the doping density in the injector regions of the cascade structures. A systematic increase in intersubband emission intensity with doping density is observed owing to the enhanced current flow through the devices, with powers of up to View the MathML source detected.