Engineering of the nonradiative transition rates in modulation-doped multiple-quantum wells

The feasibility of the enhancement of the acoustic-phonon limited intersubband transition rate through impurity scattering has been theoretically investigated in double asymmetric-coupled quantum wells. The dependence of the acoustic-phonon rate on the barrier thickness and the effect of the position of the δ-doped region on the impurity rate have been treated rigorously. A 10-Å-doped region with a 10 ¹⁰-cm^-2-sheet density can enhance the acoustic-phonon transition limit by more than an order of magnitude. This allows for the design of intersubband lasers in which population inversion between acoustic-phonon limited discrete conduction-band states is achieved by impurity scattering and control of barrier thickness