Bandgap Control for Intersubband Transition in InGaAs/AlAsSb Coupled Double Quantum Wells

This letter demonstrates bandgap control of ion-induced intermixing on InGaAs/AlAsSb coupled double quantum wells (CDQWs). With phosphorus ion implantation and different rapid thermal annealing (RTA) processes, the blueshift of the bandgap profile can be tailored. The influence of quantum well intermixing on the cross-phase modulation (XPM), caused by the intersubband transition in the CDQWs, is also experimentally investigated. Higher RTA temperature or longer annealing time could cause a larger bandgap blueshift that decreases the XPM efficiency. After annealing, the implanted CDQWs have a relatively low transmission loss, whereas the non-implanted sample can maintain a high XPM efficiency. This result can be used for monolithic integration of different bandgap modules with spatially selective mannerisms, and the implications are vast for optical communication applications.