The diffusion of Pt can be explained in terms of the kick-out and dissociative mechanisms. The resultant set of 4 coupled differential equations was here solved numerically without making any simplifications. It was found that the concentration of substitutional Pt was strongly affected by the initial vacancy concentration. A complete set of parameters was suggested which described the diffusion of Pt at temperatures ranging from 700 to 950C. The dissociative mechanism predominated at temperatures below 850C, while the kick-out mechanism predominated at temperatures above 900C. The reaction constant for the dissociative mechanism was estimated to be 1.6 x 10-14cm3/s, whereas the reaction constant for the kick-out mechanism was of the order of 0.00017/s at 700C. The use of Pt diffusion at temperatures below 850C was suggested to be a means for measuring vacancy distributions in Si.

H.Zimmermann, H.Ryssel: Journal of the Electrochemical Society, 1992, 139[1], 256-62