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Which one of the following statements is false?

Asked in NEET 2010 (Mains) · Doping and carrier concentration

• (1) Pure Si doped with trivalent impurities gives a p-type semiconductor
• (2) Majority carriers in an n-type semiconductor are holes
• (3) Minority carriers in a p-type semiconductor are electrons
• (4) The resistance of an intrinsic semiconductor decreases with increase of temperature

Step-by-step solution

Why the other options are wrong

• (1) comes from this is true: a trivalent dopant leaves bonds unfilled, and those holes become the majority carriers.
• (3) comes from this is true: in p-type material holes are the majority and the few thermally generated electrons are the minority.
• (4) comes from this is true, and it is what distinguishes a semiconductor from a metal: warming breaks more bonds, so more carriers are freed and the resistance falls.

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