The transient enhanced diffusion of B during annealing at 1700C was observed in B-implanted 4H-type material. The enhanced diffusion could be strongly suppressed by the co-implantation of C, or by pre-annealing at 900C. It was suggested that the B in this material diffused via the kick-out mechanism, with the assistance of Si interstitials; by analogy with B diffusion in Si. From the form of the Fickian diffusion tail which extended into the undamaged bulk, it was deduced that the B diffusivity could be described by:

D (cm2/s) = 1 x 10-7 exp[-4.7(eV)/kT]

Suppressed Diffusion of Implanted Boron in 4H-SiC. M.Laube, G.Pensl, H.Itoh: Applied Physics Letters, 1999, 74[16], 2292-4

Figure 27

Diffusivity of Be in 6H-SiC