1993 Volume 57 Issue 7 Pages 735-741
When the thickness of film of thin film/semi-infinite diffusion couple is not enough thin, self or impurity diffusivities determined by the so-called thin film solution may include some error and it is supposed that the thicker the film and the smaller the diffusivities, the larger the error.
In this paper, concentration profiles in the diffusion couple have been calculated numerically by setting the thickness of the film to be 0.01∼0.1 μm and values of the impurity diffusivity to be 10−16∼10−20 m2/s in consideration of the concentration dependence of interdiffusivity. With the aid of this profiles the magnitude of the error of impurity diffusivity has been evaluated.
Usually, such a small impurity diffusivity has been determined experimentally with the aid of a micro sectioning technique such as ion beam spattering or SIMS. Because the maximum value of the depth of profile determined by these technique is limited to few micron meters at most, the error due to this limitation of apparatus has been mainly studied.
