Question

In semiconductors, at room temperature

• A. the valence band is completely empty.
• B. the conduction band is completely empty.
• C. The valence band is partially empty and the conduction band is partially filled.
• D. the valence band is completely filled and the conduction band is partially filled.

Hint:

At room temperature thermal energy lifts a few electrons across the small energy gap of a semiconductor.

Answer 1

The Correct Option is C

Step 1: Test each option
Valence band completely empty is false, since most electrons stay there. Conduction band completely empty is false, since some electrons are excited into it.

Step 2: Why the others fail
Valence band completely filled would mean no holes, which is true only near 0 K.

Step 3: Result
Only the statement with both bands partly occupied is correct at room temperature.

Final Answer:
Both bands are partly filled at room temperature. \[ \boxed{\text{(C) }\text{The valence band is partially empty and the conduction band is partially filled.}} \]