Measurement and Simulation of Boron Diffusivity in Strained Si1 –xGex Epitaxial Layers

Diffusion of boron in compressively strained Si1 –xGex alloy layers grown by rapidpressure chemical vapor deposition has been studied as a function of the compositionfor 0.0006 ≤ x ≤ 0.15 and annealing temperature. The comparison of the Si1 –xGexsamples to the Si samples after rapid thermal and furnace annealing revealed a retardedB diffusion inside the strained Si1 –xGex layers. The influence of the Ge content on thedopant diffusion was also measured and simulated, demonstrating that the diffusion ofB was found to decrease with the Ge alloy content and annealing temperature. A simpleempirical expression for the B retardation is presented and incorporated into a diffusionmodel for dopants in heterostructures. Good agreement between the measured andsimulated diffusivity that includes the model for strain and chemical effects are obtained.By comparing with experimental values, our extracted (by using experiment andsimulation) B diffusivity predicted a lower value (retardation)