A semiconductor doped with a pentavalent impurity such as phosphorus becomes
Correct answer: A. n type, with electrons as the majority carriers
- A. n type, with electrons as the majority carriers
- B. p type, with holes as the majority carriers
- C. an insulator
- D. a conductor with no charge carriers
Explanation
A pentavalent atom has five valence electrons but only four are needed for bonding, so the fifth is loosely bound and becomes a free electron, making electrons the majority carriers. Doping with a trivalent impurity such as boron leaves a vacancy, a hole, and gives p type material. The crystal as a whole stays electrically neutral in both cases.
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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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