The effect of Ge content on the formation and evolution of {113} defects in SiGe alloys

The aim of this work is to study the influence of the Ge content on the {113} defects formed, after a (35 keV, 1 × 1015 Ge+/cm2) preamorphization step followed by annealing at 680 °C, in relaxed SiGe alloys. For that, plan-view Transmission Electron Microscopy (PTEM) under appropriate imaging conditions was used to study the {113} defects evolution as a function of the Ge content. Experimental results show that, increasing the Ge content results in a net reduction of both the density and the size of the {113} defects. Results analysis was performed in the framework of the “excess interstitials” model which describes perfectly the observed decrease of the {113} defects density in Si. Moreover, through a confrontation between the TEM observations and the predictions of this model, we show that the density of the interstitials contained in the defects (deduced from PTEM images) is a quasi linear function of the density of excess interstitials generated during the preamorphization step beneath the c/a interface, as calculated by the SRIM code. We conclude that collisional arguments can appropriately explain the observed evolution of the {113} defects density as a function of the Ge content. Meanwhile, the observed reduction of the {113} defects size with the Ge content, may be ascribed to a decrease of the transport capacity DiCi*, responsible for the defects growth. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)