Compared with a conductor, a pure semiconductor at room temperature has
Correct answer: A. far fewer free charge carriers, and a conductivity that rises with temperature
- A. far fewer free charge carriers, and a conductivity that rises with temperature
- B. more free carriers
- C. the same number of carriers
- D. no carriers at any temperature
Explanation
A pure semiconductor has a small energy gap, so only a few electrons have enough thermal energy to cross it at room temperature, but heating promotes many more and conductivity climbs sharply. In a metal the carrier number is fixed and heating only increases scattering, so resistance rises. Doping raises the carrier concentration enormously without needing heat.
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About PN Junction
A PN junction forms when p type and n type semiconductor regions meet, creating a depletion layer and a potential barrier. The topic covers forward and reverse bias, diode current voltage characteristics, breakdown and rectification, while distinguishing an ordinary junction diode from a transistor formed from multiple junctions.
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