Influence of injector doping density and electron confinement on the properties of GaAs/Al0.45Ga0.55As quantum cascade lasers

We report on a comparative study of GaAs/Al0.45Ga0.55As mid-infrared quantum cascade lasers. Devices differ in the mechanisms for depopulating the lower laser level. The depopulation mechanisms rely on longitudinal optical (LO) phonon emission into a single subband, into two subbands or into a set of subbands forming a miniband. The influence of injector doping density and electron confinement on device characteristics is explored experimentally and theoretically. The mechanisms limiting high temperature operation and the dynamic range are investigated. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)