Impurity-free disordering of InAsInP quantum dots

Impurity-free disordering (IFD) of the InAs quantum dots (QDs) capped with either an InP layer or an InGaAsInP bilayer is studied. The samples are coated with a Si O2 or Ti O2 dielectric layer followed by rapid thermal annealing at 700, 750, 800, and 850 °C for 30 s. A large differential energy shift of 157 meV is induced by Si O2 in the QDs capped with an InGaAsInP bilayer. Contrary to the reported results on the suppression of intermixing of GaAs based QDs by Ti O2, the authors find that intermixing of InAsInP QDs is promoted by Ti O2. X-ray photoelectron spectroscopy depth profiles show that both In and P outdiffuse to a Ti O2 layer whereas Ga, In, and P outdiffuse to a Si O2 layer leading to different degrees of intermixing. The results indicate that a group V interstitial diffusion mechanism might be responsible for IFD of InAsInP QDs.