Questions on semiconductor

Jan 10 • Notes • 6232 Views • 3 Comments on Questions on semiconductor

1. What is a semiconductor?                                                                                                        Ans.  Semiconductor are the substances which are insulators at zero kelvin and starts conducting when temperature increases. Forbidden energy gap is very less inthem as compared to insulators.Eg- Silicon

2. What are the types of semiconductor?                                                                                       Ans. It is of 2 types  a) Intrinsic                                                                                                                                             b) Extrinsic

3. What is forbidden energy gap in semiconductor? Ans. In an atom electron occupy distinct energy levels. When atoms join to make solid then energy is grouped in bands.These bands are separated by energy level in which electrons can’t exist this is called forbidden energy gap.

4. What is Doping?                                                                                                                               Ans.  The process of adding impurities to increase the conductivity of silicon and germanium crystal is called Doping and the impurity is called Dopant.

5. What is intrinsic semiconductor?                                                                                                Ans . Pure germanium and silicon crystal in their natural state is called Intrinsic semiconductor.

6.What are the types of extrinsic semiconductor?                                                                                Ans. They are of 2 types                                                                                                                    a) N-type                                                                                                                                           b)  p-type

7.Explain n-type semiconductor?                                                                                         Ans.When a impurity with 5 valence electron are added with germanium then 4 electron form covalent bond with electron and 1 moves free in crystal structure. So charge is carried by electron. Since charge carrier are negatively charged it is called n-type semiconductor.

8. Explain p-type semiconductor?                                                                                                   Ans. When a trivalent impurity is added to germanium then 3 electron form covalent bond and 1 is left blank it is called hole. Hole is free to move.Hole is positively charged so current carrier are positively charged so it is called p-type semiconductor.

9.What is amplifier?                                                                                                                        Ans. Amplifier is a device which produces enlarged version of input. It is used for increasing the amplitude of variation of alternating voltage.

10. Which diode can be operated in reverse breakdown voltage and what is its use?

Ans Zenor diode is specially designed diode which is operated in reverse breakdown voltage. Its main application is it is used as voltage regulator.

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