Accept impurity concentartion of si at 300 K is $$10^{19} cm^{-3}$$ Calculate the concentration of donor impurity atoms that should be added so that Si is n type and the Fermi Energy is 26 meV below the conduction band edge (Given: Effective density state $$N_{c} = 2.7 \times 10^{19} cm^{-3}$$ and Thermal Volatage $$(V_{T})$$ at 300 K is 26 mv)

A

$$1.5 \times 10^{19} cm^{-3}$$

B

$$3 \times 10^{19} cm^{-3}$$

C

$$ 10^{19} cm^{-3}$$

D

$$ 2 \times 10^{19} cm^{-3}$$