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.
InGaAsP/InP QW Impurity Free Intermixing for Variable ZrO2 Cap Thickness
Impurity free quantum well intermixing (IFQWI) by cap layer thickness variation for InGaAsP/InP multiquantum wells (MQWs) is reported for the first time. The blue-shift is observed to be enhanced or inhibited depending on the thickness of the ZrO2 cap layer used (100-600 nm) for anneal conditions of 600 °C-750 °C for 40 s. The group-V intermixing in InGaAsP/InP dominates the IFQWI resulting in a blue-shift of the MQW bandgap and the blue-shift increases with increasing ZrO2 thickness to 400 nm. A 600-nm ZrO2 cap is found to inhibit the blue-shift. For higher anneal temperatures similar inhibition nature is observed, with larger blue-shifts. An interdiffusion model shows that the diffusion length ratio for group-V to group-III initially increases from 1.25 to 1.6 for 100-400 nm ZrO2 thickness, but decreases to 1.1 for 600-nm ZrO2. This technique is promising for the fabrication of tapered waveguides for photonic integration of InGaAsP/InP by IFQWI.
Anomalous Annealing Behavior of Arsenic Implanted Silicon as a Function of Dose and Energy
Anomalous annealing behavior of damage in As implanted Si has been investigated by channeling effect measurements. Room temperature As implants with doses from 1014 to 2 × 1016cm-2 at energies ranging from 50 to 250 keV into Si were annealed over the range of 600°C to 1100°C. Anneal temperatures ≥ 950°C reduce the disorder for ion doses of 0.5 to 1 × 1016 cm-2 at energies between 50 and 250 keV. Anomalously high residual disorder was found for the intermediate doses of 2 × 1014 to 2 × 10/cm2 implanted above 100 keV. For this intermediate dose, annealing of implants performed at liquid nitrogen temperatures did not show significant reduction in this damage. However implants at 200° to 300°C indicate a lower amount of damage compared to the room temperature implants.