PN junctions and diodes

How is voltage applied to forward-bias a PN junction diode?

  1. AThe p side positive and the n side negative
  2. BThe p side negative and the n side positive
  3. CThe p side and n side at the same potential
Show answer and explanation

Answer: A. The p side positive and the n side negative

Making the p side (anode) positive and the n side (cathode) negative lowers the potential barrier at the junction, so majority carriers flow across it and a large current flows. This is forward bias. The opposite polarity is reverse bias, under which almost no current flows.

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More PN junctions and diodes questions

  1. What happens to the width of the depletion layer when the reverse bias applied to a PN junction is increased?
  2. Which phenomenon does a voltage-regulator (Zener) diode mainly use?
  3. Which correctly describes the relationship between forward current and forward voltage of a PN junction diode?
  4. What is the forward voltage (the approximate voltage at which current starts to flow) of a typical silicon PN junction diode?
  5. How does the reverse saturation current of a PN junction diode depend on temperature?