· Diffusion coefficient tells us how effectively does an impurity atom diffuse through the silicon wafer.
· Diffusion coefficient depends exponentially on temperature
D = D0 exp(-EA / kT)
Where D0 is the frequency factor (in cm2/sec)
EA is the activation energy in eV
T is temperature (in K)
K is Boltzmann constant in eV/K
Example: Calculate the diffusion coefficient for boron at 1100°C.
We know that D = D0 exp(-EA / kT)
T =1100°C=1100 + 273 = 1373 K
EA = 3.69 eV / K