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1. What is P-N Junction?
P-type and N-type semiconductor pieces placed together so as to form a junction.
2. Why is silicon preferref over germanium?
Silicon has high peak inverse voltage, current ratings and wider temperature range than germanium.
3. What are breakdown mechanism?
Because of the increase in reverse bias through the diode, the current abruptly increases. This sudden increase in current leads to breakdown of the junction. There are two breakdown mechanisms. Zener and avalanche Breakdown
4. In lightly doped region Avalanche breakdown take place and in heavily doped region zener breakdown take place.
5. What is an ideal diode?
A diode which has zero resistance when forward bias and infinite resistance when reverse bias.
6. Define dynamic resistance in forward bias condition
Dynamic or AC resistance is defined as the ratio of the small change in forward voltage to that of small change in forward current.
7. Germanium is more temperature dependent than silicon . Why?
This is because the reverse saturation current is case of germanium is 1000 times larger.
8. What is effect of temperature on diode?(Very very important)
Reverse saturation current increases or doubles for every 10 rise in temperature. Forward voltage has the negative temperature coefficient.that means increase in temperature leads to decrease in voltage.
9. What is step graded junction?
A junction is said to be step graded if there is an abrupt change from acceptor ion concentration on the p-side to the donor ion concentration from the n-side such as alloyed or fused junction.
10. What are two type of capacitances across the P-N junction? Which is more important in case of forward bias?
Transition and diffusion capacitances. In case of forward bias diffusion capacitance is much more important than transition capacitance.
11. What are thermistors?
Thermal + resistor = thermistor. It’s a resistor with definite thermal characteristics.
12. Why most of the thermistors have negative temperature coefficient?
This is because when the temperature increases the concentration of the charge carriers increases, thus resistance decreases.
1. What is P-N Junction?
P-type and N-type semiconductor pieces placed together so as to form a junction.
2. Why is silicon preferref over germanium?
Silicon has high peak inverse voltage, current ratings and wider temperature range than germanium.
3. What are breakdown mechanism?
Because of the increase in reverse bias through the diode, the current abruptly increases. This sudden increase in current leads to breakdown of the junction. There are two breakdown mechanisms. Zener and avalanche Breakdown
4. In lightly doped region Avalanche breakdown take place and in heavily doped region zener breakdown take place.
5. What is an ideal diode?
A diode which has zero resistance when forward bias and infinite resistance when reverse bias.
6. Define dynamic resistance in forward bias condition
Dynamic or AC resistance is defined as the ratio of the small change in forward voltage to that of small change in forward current.
7. Germanium is more temperature dependent than silicon . Why?
This is because the reverse saturation current is case of germanium is 1000 times larger.
8. What is effect of temperature on diode?(Very very important)
Reverse saturation current increases or doubles for every 10 rise in temperature. Forward voltage has the negative temperature coefficient.that means increase in temperature leads to decrease in voltage.
9. What is step graded junction?
A junction is said to be step graded if there is an abrupt change from acceptor ion concentration on the p-side to the donor ion concentration from the n-side such as alloyed or fused junction.
10. What are two type of capacitances across the P-N junction? Which is more important in case of forward bias?
Transition and diffusion capacitances. In case of forward bias diffusion capacitance is much more important than transition capacitance.
11. What are thermistors?
Thermal + resistor = thermistor. It’s a resistor with definite thermal characteristics.
12. Why most of the thermistors have negative temperature coefficient?
This is because when the temperature increases the concentration of the charge carriers increases, thus resistance decreases.
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