Quantum well intermixing caused by nonstoichiometric InP

We study the thermal stability of InP-based quantum well hetero-structures in which the temperature of growth of one or more layers is slightly reduced in comparison to standard growth. We examine the enhancement of quantum well intermixing (QWI) using repeated isothermal anneals, and show that the enhancement is a transient effect due to a surplus of mobile defects grown-in to the low temperature (LT) layers. These defects are related to a surplus of group-V atoms, and are thought to be phosphorus interstitials. The resultant interdiffusion occurs at different rates on each sublattice, thereby causing an enhancement of local strains, as observed by X-ray diffraction.