On the basis of band theory of solids the semiconductors have _____________________?
Correct answer: C. A completely filled valence band a partially filled conduction band and a narrow forbidden band
- A. A party filled valence band and totally empty conduction band
- B. A completely filled valence band a totally empty conduction band and a very wide forbidden band
- C. A completely filled valence band a partially filled conduction band and a narrow forbidden band
- D. A partly filled valence band a totally empty conduction band and a wide forbidden band
Explanation
A semiconductor has a filled valence band and a small forbidden energy gap, so some electrons can reach the conduction band at ordinary temperatures; the conduction band may then be partly occupied. The likely alternative is a, but a partly filled valence band is not the standard band description of an intrinsic semiconductor.
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About Quantum Theory and Radiation
Quantum theory treats electromagnetic radiation as packets of energy called photons, with energy proportional to frequency through E equals hf. The topic covers Planck's hypothesis, photon momentum, the photoelectric effect, threshold frequency, work function and wave particle duality, distinguishing quantised energy exchange from classical continuous radiation.
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