Intersubband absorption generation through silicon ion implantation in undoped InGaAs/AlAsSb coupled double quantum wells towards monolithic integration of intersubband-transition-based all-optical switches

We demonstrated the intersubband absorption through silicon ion implantation and subsequent rapid thermal annealing in undoped InGaAs/AlAsSb coupled double quantum wells. The effective temperature region of carrier activation for the implanted silicon ions is about 470~600 °C. For the sample with a silicon implantation dose of 1e14 cm^-2, we obtained an actual carrier density of ~ 7.5e13 cm^-2 (~75% activation efficiency) when it was annealed at 600 °C for 1 min. Simultaneously, a ~160-nm blueshift in interband absorption edge was observed, indicating quantum well intermixing (QWI). QWI and its non-uniformity were confirmed using SIMS and TEM measurements. This technique to generate intersubband absorption opens a route to fabricate monolithically integrated all-optical switches based on intersubband-transition induced cross-phase modulation.