Semiconductors

Step 1: Use the relationship between electron and hole densities.
In an intrinsic semiconductor, the product of the electron and hole densities is constant and equal to the square of the intrinsic carrier concentration: where: is the intrinsic carrier concentration, is the hole density, is the electron density.
Step 2: Find the extrinsic electron density.
For an extrinsic semiconductor, the product of the electron density and hole density is still related by: We are given:
, . Thus, the extrinsic electron density is:
Step 3: Conclusion.
Thus, the extrinsic electron density is .
Conclusion:
The correct answer is (B) .