Statement I : By doping silicon semiconductor with pentavalent material, the electrons density increases. Statement II : The n-type semiconductor has net negative charge. In the light of the above statements, choose the most appropriate answer from the options given below :

Statement - I is true but Statement - II is false.

Statement - I is false but Statement - II is true.

Both Statement I and Statement II are true.

Both Statement I and Statement II are false.

Electronic Devices PYQ — JEE Main 2021 · 26 Aug · Shift 1 · Q62 with Solution

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Correct answer: A

Analyze Statement I

Silicon is a group 14 element, so each Si atom has 4 valence electrons.

When silicon is doped with a pentavalent impurity such as P, As, or Sb, the impurity atom has 5 valence electrons.
- Four electrons form covalent bonds with neighboring silicon atoms.
- The fifth electron becomes a free electron.
Therefore, doping silicon with a pentavalent impurity increases the electron concentration.

So, Statement I is true.
Analyze Statement II

In an n-type semiconductor, electrons are the majority charge carriers.

However, the semiconductor as a whole remains electrically neutral because:
- the extra free electrons are balanced by the positively charged donor ions fixed in the lattice.
Hence, an n-type semiconductor does not have a net negative charge.

So, Statement II is false.
Choose the correct option
- Statement I: True
- Statement II: False
Therefore, the correct option is:

$\boxed{\text{A}}$
Comparison with stored correct answer

Stored correct answer is A, which matches the derived answer.

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Correct answer: A

Analyze Statement I

Silicon is a group 14 element, so each Si atom has 4 valence electrons.

When silicon is doped with a pentavalent impurity such as P, As, or Sb, the impurity atom has 5 valence electrons.
- Four electrons form covalent bonds with neighboring silicon atoms.
- The fifth electron becomes a free electron.
Therefore, doping silicon with a pentavalent impurity increases the electron concentration.

So, Statement I is true.
Analyze Statement II

In an n-type semiconductor, electrons are the majority charge carriers.

However, the semiconductor as a whole remains electrically neutral because:
- the extra free electrons are balanced by the positively charged donor ions fixed in the lattice.
Hence, an n-type semiconductor does not have a net negative charge.

So, Statement II is false.
Choose the correct option
- Statement I: True
- Statement II: False
Therefore, the correct option is:

$\boxed{\text{A}}$
Comparison with stored correct answer

Stored correct answer is A, which matches the derived answer.