Question

Question 1

Which of the following is true about energy band diagrams?

Select one:

a. Electron energy increases as you go down in an energy band diagram

b. Hole energy increases as you go up in an energy band diagram

c. Electron energy below Ec and hole energy above Ev is in the form of kinetic energy

d. Both electrons and holes seek the lowest possible energy level

e. All of these

Q2

In a semiconductor “dopant compensation” refers to the fact that some of the dopant atoms with the higher concentration are effectively cancelled out by the dopant atoms with the lower concentration.

Select one:

True

False

Q3

If a semiconductor is transparent to light with a wavelength longer than 0.55um, then what is the band-gap energy of this semiconductor in eV?

Q4

In a semiconductor at room temperature, the valence band is the :

Select one:

a. Highest completely full energy band

b. Lowest nearly empty energy band

c. Highest nearly full energy band

d. None of these

e. Lowest completely empty energy band

Q5

Each silicon atom forms covalent bonds with it’s 5 nearest neighbors, to form what is called the primitive cell.

Select one:

True

False

Answer 1

Q1.

Ans d is correct

​​​​​​Explaination

hole is electron void in Valence band.moving hole downwards is equivalent to moving electron upward which requires energy . electron energy energy increase up in band diagram and hole energy increases on moving down in diagram.both hole and electron wants to acquire lowest energy so hole tends to move upward and electron downward .

2.

Ans True

Dopant compensation refers to fact that when there is equal concentration of donors and acceptors atoms then there is no free carriers of either type.

3 .

Band gap = max energy of light getting passed without significantly absorbed

E=h×f

=6.63×10^{^-34} J/s × (C/wavelength)

=6.63×10^{^-34} J/s ×(3×10^{^8}m/s/0.55×10^{^-6} m)

=36.164×10^{^-20} j

=2.261 eV

4.

Ans d None of these

In semiconductor at room temperature lower lever is near completely full and upper lever is near completely empty.

5.

Ans -False

Each silicon atom is surrounded by four neighbors atoms