Question

Please help me

1. In degenerate p-type silicon, a. The Fermi energy is above the valence energy and below the intrinsic Fermi energy b. The Fermi energy is below the valence energy c. The Fermi energy is above the conduction energy d. The Fermi energy is below the conduction energy and above the intrinsic Fermi energy 2. A semiconductor has No 5X 1010 cm3 and N-2X 1018 cm2. It is a. b. C. d. N-type and electrons are the majority carriers P-type and holes are the majority carriers P-type and electrons are the majority carriers N-type and holes are the majority carriers 3. In intrinsic silicon at T# 300K, which of the following is true: a. b. C. d. All electrons are in the conduction band All electrons are in the valence band Some electrons are in the conduction band and some are in the valence band Freeze-out conditions are present 4. Gallium Arsenide a. b. c. d. Is a compound semiconductor Is a direct bandgap semiconductor Can emit a photon when an electron moves from the conduction to the valence band All of the above 5. In an enhancement-mode n-channel MOSFET a. The substrate is n-material b. The inversion layer exists at Ve c. Both (a) and (b) d. Neither (a) nor (b) 0 6. A unit cell is a. An arrangement of atoms that has a length of 1 b. A small repeatable volume within a larger arrangement of atoms c. Unique within a lattice structure d. Always shaped like a cube 7. In a pn junction with no voltage applied, a. The Fermi energy is constant throughout the system b. The conduction, valence and intrinsic Fermi energies bend through the space charge region c. There is no voltage across the space charge region d. Both (a) and (b)

Answer 1

Solution:

1. In degenartive semiconductor, the fermi lvel isabove the conduction band or beow the valance band.

degenrative means that the doping is very large.

So options (b) and (c) are correct.

2. Semiconductor has Nd>Na,means that the compensated semiconductor is a N- type semiconductor and electrons are themajority carriers.

So options (a) is correct.

3. In intrinsic semicnductor, electrons are in conduction band.

So options (a) is correct.

4. GaAs is a compound semiconductor beacause it is a combination of Ga and As and alsodirect band gap and it can emit photons as light.

So,ptions (d) is correct.

5. In enhanceent mosfet, substrate is p - type and inversion layer exixts for Vg>Vt,

So both are wrong

So options (d) is correct.

6. Unit cell is an arragement of atoms that has a length of unity.

So options (a) is correct.

7. PN junction with no voltage applied means that it remains in equilibruim condition and fermi level is constant and valancy, conduction and intrinsic energy levels bend at the junction interface

So options (d) is correct.