Cap Layer Influence on Impurity-Free Vacancy Disordering of InGaAs/InP Quantum Well Structure

Quantum well intermixing (QWI) by the impurity-free vacancy disordering (IFVD) technique is an important and effective approach for the monolithic integration of optoelectronic devices based on InGaAs/InP quantum well structures. We experimentally investigate the influence of the capping layer SiO₂ and Si₃N₄ on the QWI by IFVD. The results show that for all the samples with three-types differently doped (P, N and I) top InP layers, Si₃N₄ can always induce a larger photoluminescence blueshift than SiO₂ in the IFVD QWI process, which attributes more to the group III and V vacancies point defects created in the interface of Si₃N₄-InP than that of SiO₂-InP, proved by the SIMS measurements. The inherent mechanisms for explaining these properties are further discussed.