Detailed investigation of Ge-Si interdiffusion in the full range of Si 1 − x Ge x ( 0 ≤ x ≤ 1 ) composition

Based on the recently developed M Cs 2 + secondary ion mass spectrometry methodology, the Ge-Si interdiffusion has been investigated, using Ge(:B) solid sources, for Ge concentrations between 0 and 100 at . % . A strong dependence of the interdiffusion with the Ge content of SiGe alloys, formed during annealing, has been shown. The Boltzmann-Matano method was used to extract the interdiffusivity values for all the temperatures studied (750, 800, 850, and 900 ° C ) in the full range of SiGe compositions. Two regimes of interdiffusion have been identified, both exhibiting an exponential increase in the interdiffusion coefficient as a function of the Ge concentration. The high Ge content regime ( > 65 at . % ) is in good agreement with the values known in the "extreme" cases of Ge diffusion in Si ( 0 at . % ) , Ge self-diffusion, and Si diffusion in Ge ( 100 at . % ) , while in the low Ge content regime ( < 50 at . % ) , the presence and evolution of misfit dislocation can explain the important values of interdiffusivity found in this work. The observed results are perfectly reproduced by a simple empirical model in which the effect of the Ge concentration and the presence of misfit dislocations are taken into account. Based on the evolution of B delta layers (in Si) and Ge depth profiles during NH 3 annealing, we showed that the Ge-Si interdiffusion is predominately assisted by a vacancy mechanism with a slightly interstitial contribution in the full range of Ge concentrations. We have estimated the interstitial fraction coefficient, f Ge - SiI , to ∼ 0.17 at 900 ° C . Finally, the effect of in situ B doping is studied, which is found to induce a retardation of the Ge-Si interdiffusion.