Answer as many as you can please. They are TRUE/FALSE questions. 1. LEDs cannot

Question

Answer as many as you can please. They are TRUE/FALSE questions.

1. LEDs cannot be made of silicon because silicon is an indirect bandgap semiconductor, for the same reason optical detectors cannot be made of silicon either.

2. A blue LED is made of a wider bandgap material compared to a red LED.

3. By adding impurities that facilitate and accelerate carrier recombination, solar cell effiencies can be improved.

4. A Zener diode with higher doping concentrations has a lower break-down voltage.

5. Reduction of the base width in a BJT results in higher output resistance for the transistor (less change in collector current versus collector voltage.

6. Increasing the base doping level in a NPN BJT improves both current gain and output resistance of the transistor.

7. A BJT with doping concentrations of Ne= Nc = 1018 cm-3, and Nb=1016 cm-3, with a very narrow base can potentially have a high current gain but will for sure have a low output resistance.

8. In a p-channel J-FET, pinch off occurs at the lower potential end of the channel.

9. For n-channel MOSFETS increasing the doping level of the semiconductor substrate results in increasing Vt.

10. Reduction of the gate oxide thickness reduces the threshold voltage of n-channel MOSFETS.

11 Threshold voltage for ideal (enhancement mode, normally off) p-channel MOSFETS has a negative value.

12. Too much positive trapped charge in the gate oxide of a p-channel MOS transistor can result in a transistor which is "ON" even with Vgs=0v (depletion mode transistor).

13 Work function of Aluminum is smaller than the distance between conduction band of silicon and vacuum level, therefore, Aluminum contacts with n-type silicon result in Schottkey junctions.

14 By reducing the doping level of the channel in a JFET absolute value of pinch off voltage decreases.

15 Using a high-k dielectric (dielectric with high dielectric constant) for gate insulator reduces the threshold voltage for n-channel MOSFETS.

Explanation / Answer

1.true

2.false

3.true

4.true

5.false

6.true

7.true

8.false

9.false

10.true

11.true

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.