# Fermi Level in a Semiconductor having Impurities MCQ’s

This set of Electronic Devices & Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Fermi Level in a Semiconductor having Impurities”.

1. Which of the following expression represent the correct formulae for calculating the exact position of the Fermi level for p-type material?
a) EF = EV + kTln(ND / NA )
b) EF = -EV + kTln(ND / NA )
c) EF = EV – kTln(ND / NA )
d) EF = -EV – kTln(ND / NA )

2. Where will be the position of the Fermi level of the n-type material when ND=NA?
a) Ec
b) Ev
c) Ef
d) Efi

3. Which states get filled in the conduction band when the donor-type impurity is added to a crystal?
a) Na
b) Nd
c) N
d) P

4. When the temperature of either n-type or p-type increases, determine the movement of the position of the Fermi energy level?
a) Towards up of energy gap
b) Towards down of energy gap
c) Towards centre of energy gap
d) Towards out of page

5. If the excess carriers are created in the semiconductor, then identify the correct energy level diagram.

a)

b)

c)

d)

6. Ef lies in the middle of the energy level indicates the unequal concentration of the holes and the electrons?
a) True
b) False

7. Is it true, when the temperature rises, the electrons in the conduction band becomes greater than the donor atoms?
a) True
b) False

8. If excess charge carriers are created in the semiconductor then the new Fermi level is known as Quasi-Fermi level. Is it true?
a) True
b) False

9. Consider a bar of silicon having carrier concentration n0=1015 cm-3 and ni=1010cm-3. Assume the excess carrier concentrations to be n=1013cm-3, calculate the quasi-fermi energy level at T=300K?
a) 0.2982 eV
b) 0.2984 eV
c) 0.5971 eV
d) 1Ev

10. From the above equation, assuming the same values for the for ni, n= p and T. Given that p0=105cm-3. Calculate the quasi-fermi energy level in eV?
a) 0.1985
b) 0.15
c) 0.1792
d) 0.1