According to Fair's well-established model [Fai81] we express the
diffusion coefficient 
as sum of several diffusivities, each accounting
for impurity interactions with vacancies in different charge
states (3.2-8). The individual
diffusivities obey Arrhenius laws 
, values are
summarized in Table 3.2-1. The intrinsic carrier
concentration 
is calculated using (approximations to) Morin and
Maita's [Mor54] empirical model (Table 3.2-2).
