Few Tips Class 12 students from Semiconductor Chapter
SEMICONDUCTOR MATERIALS & PROPERTIES
1. A pure semiconductor has negative temperature coefficient of resistance
2. Majority of semiconductor devices are temperature devices
3. The mobility of electrons as well as of holes in a semiconductor decreases with increases in temperature but it is independent of the number density of the electrons or holes
4. Semiconductor devices are current controlled devices
5. An ideal junction diode when reverse biased offers infinite resistance and acts as an open circuit
6. Potential barrier at p-n junction opposes the forward current but aids the reverse current
7. Transistor can be used as an amplifier and oscillator but not as a rectifier
8. Common emitter transistor amplifier is preferred over common base transistor amplifier due to large current gain
9. If there is no forbidden band, the solid behaves as good conductor
10. The word transistor refers to transfer of resistance
11. At absolute zero temperature semiconductor behaves as a perfect insulator
12. The doping of semiconductor with small amount of impurity drastically increases their conductivity
13. Electron mobility is higher than that of holes
14. At higher temperature, the conductivity of the semiconductor increases because of the increase in the number density of the charge carriers
15. The d.c current gain is always less than 1
16. During forward bias, the depletion region becomes thin and the junction diode offers a low resistance to the motion of charge carriers.
17. Conduction electrons have more mobility than they require
18. Depletion region in the junction diode contains charges which are fixed donor and acceptor ions.
19. In unbiased p-n junction, the junction current at equilibrium is ZERO because in this condition ,there is no charge which can cross the junction.
20. The solar cell is a device which converts solar energy into electrical energy.
21. Photodiode always operates in reverse bias.
22. In p-n junction diode, holes travel from p region to n region because there is a greater concentration of holes in p-region as compared to n-region.
23. When semiconductor is unbiased, drift current and diffusion current are equal in magnitude and opposite in direction.
24. When semiconductor is forward biased, the width of depletion layer decreases.
25. An ideal junction diode when forward biased offers zero resistance and when reverse biased, has infinite resistance.
26. The maximum reverse voltage the diode must withstand is called peak inverse voltage (PIV)
27. Magnitude of direct current which can be handled by diode is called current rating of diode.
28. When transistor is operated in cut-off region or saturation region, it works as a switch.
29. An oscillator is an electronic circuit which generates AC output signal without required input signal .
30. The LC oscillators are produced by parallel combination of inductor & capacitor.
31. The process of injecting a fraction of output energy back to input by some device is called feedback.
32. Boolean algebra is developed by English Mathematician George Boole.
