It was noted that systematic errors were likely to affect the results of indirect methods for the measurement of dopant diffusion in semiconductors; which should be considered as being mixed electronic-ionic conductors. The greatest contribution to these errors was introduced by the presence of an internal electric field (space-charge effect). Such a field could be the result of a dopant concentration gradient or of an external bias which was applied during the measurements. Three methods were considered in detail. These were the measurement of p-n junction motion, of current or potential decay, and of the time-dependence of capacitance (transient ion drift). It was shown that space-charge effects could lead to the over-estimation, of diffusion coefficients, by some orders of magnitude.

I.Lubomirsky, K.Gartsman, D.Cahen: Journal of Applied Physics, 1998, 83[9], 4678-82