Question

Read the scenario given below and answer the questions that follow.   [5]

Annie, a student of Physics, began her experiment by fabricating a p-n junction diode from an extrinsic semiconductor crystal, leading to the formation of a depletion region and a potential barrier at the interface. She then measured resistance of the diode in the linear region of the V-I characteristic curve. She also studied its characteristics during forward bias and reverse bias. Finally, she designed a circuit to convert ac voltage to dc voltage.

1. Which instrument was used by Annie to measure current flowing through the diode during its reverse bias?
2. How did Annie obtain an extrinsic semiconductor from an intrinsic semiconductor?
3. What is meant by potential barrier?
4. Draw a labelled circuit diagram of a half wave rectifier.

Answer 1

(i) A microammeter is used to measure the current during reverse bias because the current is very small (in the microampere range).

(ii) An extrinsic semiconductor is obtained by doping an intrinsic semiconductor with a small and controlled amount of impurity atoms (trivalent or pentavalent) to increase its conductivity.

(iii) The potential barrier is the potential difference developed across the p-n junction due to diffusion of charge carriers, which opposes the further flow of majority carriers across the junction.

(iv)