The diffusivity was studied under extrinsic and intrinsic conditions at between 900 and 1150C. It was found that, under extrinsic conditions, the P diffusion coefficients depended upon the molar ratio of PH3 to SiH4, were larger than the reported intrinsic diffusion coefficient, and increased with molar ratio. The values of the activation energy under these conditions tended to decrease slightly from 2.49 to 2.14eV. The dependence of the diffusion coefficients on the molar ratio was explained in terms of the Fermi level effect and the existence of excess vacancies.

Phosphorus Diffusion into Silicon under the Condition of Controlled Surface Concentration. S.Matsumoto, T.Niimi: Japanese Journal of Applied Physics, 1976, 15[11], 2077-82

Figure 10

Diffusivity of P in Si