Electronic Devices - Semiconductors - Discussion
Discussion Forum : Semiconductors - General Questions (Q.No. 17)
17.
What types of impurity atoms are added to increase the number of conduction-band electrons in intrinsic silicon?
Discussion:
13 comments Page 1 of 2.
Basha said:
1 decade ago
Si has 4 valence electrons. if pentavalent impurity added then only we will get more no. of condution electrons.
Pooja said:
1 decade ago
Bivalent, octavalent are stable atoms. Here, only pentavalent and trivalent are unstable. In Q. No. Of conduction -band electrons is to be increased. So pentavalent. It can donate 1 electron. Trivalent itself needs 1 electron to b stable.
Sumit said:
1 decade ago
Why not trivalent? this may also increase conduction region.
Nithya Sivakumar said:
1 decade ago
@Sumit.
The trivalent impurities will have only 3 atoms to share. So this will not produce the increase in number of conduction band electrons. So, for a silicon to be filled with valency shell of 8 electrons, it will leave a hole. And thus it increases the number of hole only. Here the question is to increase the number of electrons.
Have you got my friend?
The trivalent impurities will have only 3 atoms to share. So this will not produce the increase in number of conduction band electrons. So, for a silicon to be filled with valency shell of 8 electrons, it will leave a hole. And thus it increases the number of hole only. Here the question is to increase the number of electrons.
Have you got my friend?
Priyanka said:
1 decade ago
But by adding pentavalent impurity, holes percentage increases not electron.
Riyazali said:
1 decade ago
As we know each silicon atom has 4 electrons in valence band when we dope with pentavalent impurity like phosphorous which has 5 electrons in valence band. 4 out of 5 in Phosphorous form a covalent bond with si atoms. We left with single electron. That acts as free electron in which helps for conduction.
Binod said:
1 decade ago
Pentavalent and trivalent both b can use for increasing the conduction of intrinsic semiconductor.
If penta then n type & if trivalent then p type.
If penta then n type & if trivalent then p type.
Pallavi said:
1 decade ago
As we want to improve the the number of electrons in conduction band not holes so we have to added pentavalent impurities to intrinsic semiconductor.
Bob said:
9 years ago
Intrinsic is a pure semiconductor how to add impurities?
K biswas said:
8 years ago
Yeah, I agree with bob, its intrinsic so no impurity will be added.
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