 |
||
 |
 |
 |
|
||
|
|
|
Solid-Solubility Limits
At a given temperature, there is an upper limit to the amount of an impurity which can be absorbed by Si. Shown below is the solid-solubility limits for several impurities in Si.
Successive Diffusions
To compute the total effect of many cycles of diffusion
(Dt)tot = S D1t1 + D2t2 + D3t3 . . . . .where
t1,t2,t3... are the different diffusion times and D1,D2,D3... are the appropriate diffusion constant in effect during these times.
Lateral Diffusion
During diffusion, impurities not only diffuse vectically but also move laterally under the edge of any diffusion barrier.