Influence of SiO2 and TiO2 dielectric layers on the atomic intermixing of InxGa1−xAs/InP quantum well structures
We have studied the influence of SiO2 and TiO2 dielectric layers on the atomic intermixing of InxGa1−xAs/InP quantum well structures using the impurity-free vacancy disordering technique. Photoluminescence results revealed that an enhancement of interdiffusion was obtained when the samples were capped with SiO2. Although TiO2 layers were able to suppress the interdiffusion in the InGaAs/InP system, the suppression was not significant compared to the AlGaAs/GaAs system. Based on a fitting procedure that was deconvoluted from the photoluminescence spectra as well as a theoretical modeling, the electron–heavy hole and electron–light hole transitions were identified, and a ratio of the group V to the group III diffusion coefficients (k) was obtained. The k ratio of the InGaAs/InP samples capped with SiO2 is relatively larger than that of samples capped with TiO2 layers.
A comparison of spectroscopic and microscopic observations of ion-induced intermixing in InGaAs/InP quantum wells
Using n-doped InGaAs/InP multi-quantum-well samples we compare measurements of ion-beam-induced quantum well broadening made by cross-sectional scanning tunneling microscopy and cross-sectional scanning transmission electron microscopy with the broadening calculated from the blueshift of the low temperature photoluminescence peak using different models of the intermixing process. Results are consistent with a simple square well model used to interpret photoluminescence shifts, but disagree with a model of separate Fick’s law diffusion on group III and V sublattices.
MODELING OF THE ION MASS EFFECT ON TRANSIENT ENHANCED DIFFUSION : DEVIATION FROM THE +1' MODEL
The influence of ion mass on transient enhanced diffusion (TED) and defect evolution after ion implantation in Si has been studied by atomistic simulation and compared with experiments. We have analyzed the TED induced by B, P, and As implants with equal range and energy: TED increases with ion mass for equal range implants, and species of different mass but equal energy cause approximately the same amount of TED. Heavier ions produce a larger redistribution of the Si atoms in the crystal, leading to a larger excess of interstitials deeper in the bulk and an excess of vacancies closer to the surface. For high-mass ions more interstitials escape recombination with vacancies, are stored in clusters, and then contribute to TED. TED can be described in terms of an effective “+n” or “plus factor” that increases with the implanted ion mass.