Higher H diffusivities were observed in some solar-cell materials than in Czochralski or float-zone wafers. Secondary ion mass spectroscopic profiles of H or D, which had been implanted at low energies and at temperatures ranging from 100 to 300C, were compared for various types of Si substrate. The data could be described by the expressions:

polycrystalline:     D (cm2/s) = 0.0001 exp[-0.50(eV)/kT]

Czochralski: D (cm2/s) = 0.0001 exp[-0.58(eV)/kT]

float-zone: D (cm2/s) = 0.0001 exp[-0.56(eV)/kT]

It was found that the presence of O seemed to lower the grain-boundary diffusivities.

B.L.Sopori, K.Jones, X.J.Deng: Applied Physics Letters, 1992, 61[21], 2560-2