2011, Vol.14, No.1, pp.70-79
Analytical solution of the equations describing impurity diffusion
due to the migration of nonequilibrium impurity interstitial atoms
was obtained for the case of the Robin boundary condition on the
surface of a semiconductor. The solution obtained can be useful
for verification of approximate numerical solutions, for
simulation of a number of processes of interstitial diffusion, and
for modeling impurity diffusion in doped layers with the
decananometer thickness because in these layers a disequilibrium
between immobile substitutionally dissolved impurity atoms,
migrating self-interstitials, and migrating interstitial impurity
atoms can take place. To illustrate the latter cases, a model of
nitrogen diffusion in gallium arsenide was developed and
simulation of nitrogen redistribution from a doped epi-layer
during thermal annealing of GaAs substrate was done.
The calculated impurity concentration profile agrees well with
experimental data. The fitting to the experimental profiles
allowed us to derive the values of the parameters that describe
interstitial impurity diffusion.
Key words:
diffusion modeling, equation solution, interstitial,
nitrogen, gallium arsenide
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