Pls answer all questions Problem 1. Please choose the best answer to each ofthe
ID: 2083155 • Letter: P
Question
Pls answer all questions Problem 1. Please choose the best answer to each ofthe following questions, 2 pts. each. You may provide information to support your answer for possible l pt. partial credit (if you chose the incorrect answer) (40 pts, total) A. Electromagnetic waves include: 1. X-rays. 2. Protons 3. Phonons 4. None of the above. B. The p-n junction is the basic device structure for many photonic devices. This is because: 1. Arsenic can be used as a p-type dopant. 2. Sun light is mostly yellow. 3. Boron can be used as a p-type dopant. 4. The built-in potential is useful for device operations. C. A solar cell can be fabricated fro 1. A indirect bandgap semiconductor. 2. A direct bandgap semiconductor. 3. Silicon. 4. All of the above. D. LEDs generally use: 1. Indirect bandgap semiconductors because radiative transitions from the conduction band to valence band have a high probability. 2. Direct bandgap semiconductors because radiative transitions from the valence band to conduction band have a low probability. 3. Direct bandgap semiconductors because radiative transitions from the conduction band to valence band have a high probability. 4. Indirect bandgap semiconductors because radiative transitions from the conduction band to valence band have a low probability. E. For a given quantum well the energies of the quantized electron energy states are given by Es-2.5 evn n-1.2.3... From this, the energy of photon emitted when an electron makes a transition from the n 2 state to the n 1 state is: 1.6 eV 2.7.5 eV 3.6.5 eV 4, 4,5eVExplanation / Answer
A- (1)
X-rays are the Electromagnetic waves. Hence the correct answer is 1.
B- (4)
As the p-n junction has a built in potential , it is useful for acting a p-n junction like switch or many other operations. Hence correct answer is 4.
C-( 4)
A solar cell can be made from all of the given three semiconductors.
D- 3
The led generally use direct bandgap because the law of momentum conservation must be satisfied. In case of direct bandgap, it is most probable that electrons from conduction band transmit yo valence band releasing energy.
According to chegg guidelines I have answered first 4 questions. PlEASE PROVIDE A GOOD RATING IF THIS HELPED.