Simultaneous generation of intersubband absorption and quantum well intermixing through silicon ion implantation in undoped InGaAs/AlAsSb coupled double quantum wells

We demonstrated the intersubband absorption in undoped InGaAs/AlAsSb coupled double quantum wells through silicon ion implantation and rapid thermal annealing. For an implantation dose of 1×1014 cm−2, the actual carrier density of a sample annealed at 600 °C for 1 min was ∼7.5×1013 cm−2 (∼75% activation efficiency); the activation energy was ∼1.41 eV. The simultaneously generated quantum well intermixing (QWI) was nonuniform due to the silicon ion distribution. The effects of QWI nonuniformity on both intersubband and interband transitions were explained by eight-band k⋅p calculation. This study will open a route for monolithic integration of intersubband-transition-based high-speed all-optical switches.