The barrier potential across an unbiased silicon pn junction is about
Correct answer: B. 0.7 V
- A. 0.3 V
- B. 0.7 V
- C. 5 V
- D. 12 V
Explanation
Silicon has a barrier of roughly 0.7 V, while germanium's is about 0.3 V, which is why a silicon diode needs about 0.7 V across it before it conducts appreciably. This forward voltage drop must be allowed for in circuit calculations. Silicon is preferred for most applications because it tolerates higher temperatures and has lower leakage.
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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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