The diffusion of B in compressively strained SiGe alloy layers, grown via rapid pressure chemical vapour deposition, was studied as a function of Ge atomic fractions ranging from 0.06 to 15%. A comparison of the SiGe samples with Si samples, following rapid thermal and furnace annealing, revealed the occurrence of retarded B diffusion within the strained SiGe epitaxial layers. The effect of the Ge content upon dopant diffusion was also measured and simulated. This demonstrated that B diffusion (figure 17) and band-gap changes decreased with the Ge content. The activation energies for diffusion increased with increasing Ge content, within the investigated composition range. A simple empirical expression for B retardation was incorporated into a diffusion model for dopants in heterostructures. Good agreement between measured and simulated diffusivities was obtained, upon including strain and chemical effects.

Studies of Boron Diffusivity in Strained Si1-xGex Epitaxial Layers. K.Rajendran, W.Schoenmaker: Journal of Applied Physics, 2001, 89[2], 980-7