Exam Questions Papers - Engineering

Q1:

Silicon is doped with boron to a concentration of 4 x 1017 atoms/cm3. Assuming the intrinsic carrier concentration of silicon to be 1.5 x 1010/cm3 and the value of to be 25mV at 300K. Compared to undoped silicon, the Fermi level of doped silicon

A goes down by 0.13 eV

B goes up by 0.13 eV

C goes down by 0.427 eV

D goes up by 0.427 eV

ANS:C - goes down by 0.427 eV

Use EF - Ev = Since it is doped with acceptor impurity, Fermi level will shift down.