Abstract
We investigated the multiple cations intermixing in InAs/InGaAlAs quantum dot-in-well laser structure gown on InP substrate using impurity-free vacancy disordering (IFVD) technique. Selective control of the bandgap shifts has been achieved using SiO2 and SixNy annealing caps. A differential wavelength shift of 76 nm has been observed after a rapid thermal annealing step at 750 degrees C for 30 s. In contrast to most IFVD results in other materials, we observed a larger bandgap shift from the SixNy capped samples than from the SiO2 capped samples. Based on theoretical calculations, we attribute this to the different effective interdiffusion rates of group-III cations. The demonstrated intermixing process provides an effective method for fine tuning the bandgap of InAs QDs around 1.55 mu m as an alternative to the growth manipulation, as well as for realizing photonics integrated circuits.