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At absolute zero, Si acts as

Asked in CBSE AIPMT 1988 · Conductors, insulators and semiconductors

Answer: (3) insulator

Step-by-step solution

Idea: conduction needs electrons in the conduction band, and at 0 K there is no thermal energy to put them there.

Silicon's valence band is completely full at absolute zero and its conduction band completely empty.

A full band carries no net current, so the crystal cannot conduct at all.

At 0 K silicon therefore behaves as an insulator; it is only at higher temperatures that it becomes a semiconductor.

Why the other options are wrong

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