Question

An intrinsic semiconductor has ${10}^{18}/m^3$ free electron and is doped with pentavalent impurity of ${10}^{24}/m^3$. Then the free electrons density order increase by

• A. $4$
• B. $3$
• C. $5$
• D. $6$

Answer 1

Answer: (D)

$6$

Given that, free electron density in intrinsic semiconductor is ${10}^{18}/m^3$. When it is doped with a pentavalent impurity of density ${10}^{24}/m^3$, then the free electrons are donated and thus density order of free electrons increase by $(24-18=6)$.