The interdiffusion of Si/Si 0.85 Ge 0.15 /Si single quantum well ͑SQW͒ structures subjected to inert-and oxidizing-ambient annealing was investigated as a function of temperature ͑900-1200°C͒ and time. Point defect injection allowed modification of the vacancy and interstitial mediated components of interdiffusion, D V and D I . Diffusion profiles of samples processed in inert and oxidizing ambients were similar, which indicates a vacancy-dominated mechanism. Activation energies of diffusion in inert and oxidizing ambients were found to be 5.8 and 5.0 eV, respectively. A fractional interstitial component f I of ϳ0.10 was estimated for the lower temperatures, while a significantly smaller f I of ϳ0.02 was estimated for the higher temperatures. Experiments using SQWs with buried boron marker layers showed that dislocations in the Si 1-x Ge x trap point defects and affect interdiffusion behavior.

Interdiffusion of Si/Si0.85Ge0.15 heterojunctions subjected to annealing in inert and oxidizing ambients was investigated as a function of temperature (900 to 1200 °C) and time, allowing comparison between intrinsic diffusion and diffusion under interstitial injection. The Ge diffusivity was extracted using the process simulation program FLOOPS. A time-independent diffusivity was observed for all temperatures. The calculated Ge diffusivity in oxidizing ambient was comparable to that in inert ambient indicating that the interstitial concentration plays a minimal role in interdiffusion. A fractional interstitial component, f1, equal to 0.10 is estimated for annealing temperatures in the range 900 to 1100 °C, while f1 increases to approximately 0.17 at 1200 °C. This may indicate a change in diffusion mechanism at a temperature greater than 1100 °C

The interdiffusion of a Si/Si 0.85 Ge 0.15 /Si single quantum well heterostructure subjected to thermal annealing in a nitriding ambient was investigated as a function of anneal temperature and time. Nitridation of the silicon surface alters equilibrium vacancy point defect populations throughout the structure, which allows the determination of the point defect species important in interdiffusion. Diffusion coefficients of Ge after nitridation of ϳ1ϫ10 Ϫ14 cm 2 /s for 1100°C and ϳ1 ϫ10 Ϫ13 cm 2 /s for 1200°C were extracted. The extent of diffusion in a nitriding ambient was much less than in an inert ambient, which indicates minimal vacancy contribution to interdiffusion. This is in contrast to results from previously published studies performed in an oxidizing ambient.

Carbon is a native impurity in Si which is known to trap self-interstitials and decrease their diffusivity. Carbon has also been observed to decrease B transient enhanced diffusion (TED) in Si through these interstitial interactions. Recently it has been proposed that vacancies must also be considered when accounting for the reduction of B TED. We have incorporated both the kick-out mechanism and the Frank-Turnbull (F-T) mechanism in simulations of interstitial diffusion and carbon diffusion, as well as experiments involving B diffusion in B doped superlattices (DSLs) with varying C concentration regions. We have used the binding energy between a carbon atom and a self-interstitial as a basis for the reaction rates for both mechanisms, and have found that an single energy of 2.25 eV best reproduces the results from several experiments, assuming equilibrium initial conditions for both mechanisms and ab-initio equilibrium values for all point defects.

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