Si-implanted, unstrained Si1−xGex layers of various Ge concentrations ranging from 0% to 50% were grown by molecular beam epitaxy on top of a Si substrate. The samples were subjected to a 750 °C anneal for 180 min to explore the subsequent defect structure. Plan-view transmission electron microscopy was implemented to investigate the evolution of defects. The Si1−xGex samples with ⩽5% Ge exhibit {311} defect formation and dissolution, and these defects ripen throughout the course of the anneal. Increasing the Ge content has an adverse effect on the growth of {311} defects. The samples with Ge contents ⩾25% demonstrated only dislocation loop formation. Dislocation loop formation and the observed impedance of {311} defect growth is facilitated by increasing the Ge content due to the weak bonding associated with the Ge atoms.
The relationships between extended defect evolution and boron diffusion in Si0.77Ge0.23 have been investigated. A SiGe structure was grown by molecular beam epitaxy with a 3×1018atoms∕cm3 boron marker layer positioned 0.50μm below the surface. Samples were ion implanted with 60 keV Si+ at a dose of 1×1014atoms∕cm2 and subsequently annealed at 750 °C for various times. The evolution of extended defects in the near surface region was monitored with plan-view transmission electron microscopy. Secondary ion mass spectroscopy concentration profiles facilitated the characterization of boron diffusion. Boron experiences transient enhanced diffusion regulated by the dissolution of dislocation loops. The maximum diffusion enhancement in Si0.77Ge0.23 is less than that observed in pure Si.
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