代写VE320 Intro to Semiconductor Devices Summer 2024 — Problem Set 3代写Web开发

VE320 Intro to Semiconductor Devices

Summer 2024 — Problem Set 3

Due: 11:59pm 12th June

1)  Explain the physical meaning of the Fermi energy level.

2) A silicon piece at T = 300K has  Na   = 7 × 1014cm−3 and  p0  = 2 × 105 cm−3

a) Is the material n type or p type?

b) What are the majority and minority carrier concentrations?

c) What must be the concentration of donor impurities?

3)  Silicon is doped at  Nd   = 1015cm−3and  Na   = 0.

a) Plot the concentration of electrons versus temperature over the range 200K ≤ T ≤ 600K. (qualitatively)

b) For the device to operate properly, the intrinsic carriers must contribute no more than 5 percent to the total electron concentration. Calculate the maximum temperature it can work out.

4) The magnitude of the product  gc (E)fF (E) in the conduction band is a function of energy. Assume the Boltzmann approximation is valid.

a) Determine the energy with respect to  Ec    at which the maximum occurs.

b) Repeat part a) for the magnitude of the product  gv (E)[1 − fF (E)] in the valence band.

5) For a particular semiconductor,  Eg   = 1. 50ev,  mp(∗) = 10mn(∗) , T = 300K, and  ni   = 1 ×

105 cm−3 .

a) Determine the position of the intrinsic Fermi energy level with respect to the center of the bandgap.

b) Impurity atoms are added so that the Fermi energy level is 0.45eV below the center of the bandgap. Assume complete ionization.

i) Are acceptor or donor atoms added?

ii) What is the concentration of impurity atoms added?

6) A particular semiconductor material is doped at  Nd   = 2 × 1014cm−3 , and  Na   = 1.2 ×

1014cm−3 . The thermal equilibrium electron concentration is found to be  n0   = 1.1 × 1014cm−3 . Assuming complete ionization, determine:

a)  the intrinsic carrier concentration

b)  the thermal equilibrium hole concentration

7)

a)  What is meant by complete ionization?

b)  What is meant by freeze-out?