2.2. Formation of Depletion Region

Try these first

1. 1.

   What happens to electrons when p-type and n-type materials are joined?

   Hint

   Think about where each type of carrier is located.

2. 2.

   Define the term 'depletion region'.

   Hint

   Focus on what happens to charge carriers.

3. 3.

   What forms the depletion region?

   • A: Movement of electrons only
   • B: Recombination of charge carriers
   • C: Application of external voltage

   Hint

   Think about what happens when charge carriers meet.

4. 4.

   True or False: The depletion region widens when a PN junction is forward-biased.

   • True
   • False

   Hint

   Consider what happens when voltage is applied.

5. 5.

   Consider a PN junction diode with a built-in potential of 0.7 V. Calculate the necessary external voltage to forward bias this diode and allow current to flow.

   Hint

   Consider the needed voltage versus what is already present.

6. 6.

   Explain how changes in temperature affect the width of the depletion region in a PN junction.

   Hint

   Think about how thermal energy influences carrier mobility.