Use of a buried loop layer as a detector of interstitial flux during oxidation of SiGe heterostructures

The injection of interstitials from oxidation of Si and SiGe has been investigated quantitatively using transmission electron microscope (TEM) to monitor the growth of a layer of implantation induced dislocation loops. The layer of loops was introduced via a 50 keV P implant at a dose of 2 × 1014/cm2 followed by annealing at 750 °C. Subsequently, silicon–germanium containing heterostructures, consisting of a 5 nm silicon cap on top of either a 20 nm Si0.7Ge0.3 layer or 25 nm Si layer were grown on the implanted wafers. The wafers were then oxidized, and the trapped interstitials in the dislocation loops were determined via quantitative plan view TEM. It is shown that the SiGe layer and the inherent epitaxial interfaces are fully transparent to a flux of interstitials arising from the oxidizing interface. As expected, oxidation of the Si control and Si on SiGe result in strong interstitial injection. However, for the latter sample, as the oxidation front proceeds into the SiGe layer, interstitial injection...