Electronic Devices and Circuits Interview Questions and Answers for Experienced people on “The Current Components in a P-N junction diode”.
1. When a forward biased is applied to a diode, the electrons enter to which region of the diode?
A. P-region
B. N-region
C. P-n junction
D. Metal side
Answer: A
Clarification: When the forward biased is applied, the electrons enter to the p-region and the holes enter to the n-region so that holes can flow from p-region to n-region. Whereas, the electrons can travel from n-region to p-region.
2. The number of injected minority carriers falls off linearly with the increase in the distance from the junction. Is it true or false?
A. True
B. False
Answer: B
Clarification: The number of minority carriers fall off exponentially rather than linearly with the increase in the distance from the junction.
3. What is the total current in a diode when x=0?
A. I = Ipn (0) – Inp (0)
B. I = Ipn (0) + Inp (0)
C. I = -Ipn (0) – Inp (0)
D. I = -Ipn (0) + Inp (0)
Answer: B
Clarification: At junction, the total current is equal to the minority hole current plus the minority electron current.
4. The current in the diode is
1. Unipolar
2. Bipolar
A. I only
B. II only
C. I and II both
D. Neither I nor II
Answer: B
Clarification: The current in the diode consists of both the electrons and holes. So, it is bipolar.
5. The current is constant throughout the device. Is it true or false?
A. True
B. False
Answer: A
Clarification: The current in the device is constant but the proportion due to the electrons and holes varies with distance.
6. Which of the following statements is correct under forward biased p-n diode?
A. current enters n side as hole current and leaves p side as electron current
B. current enters n side as electron current and leaves p side as hole current
C. current enters p side as hole current and leaves n side as electron current
D. current enters p side as hole current and leaves p side as electron current
Answer: C
Clarification: When the current flows in a p-n diode, the current enters p side as hole current and leaves n side as electron current.
7. Calculate the total current when Ipn (0)=1mA and Inp (0)=2mA.
A. 1mA
B. -1mA
C. 0
D. 3mA
Answer: D
Clarification: I=Ipn (0)+Inp (0)
=1mA+2mA
=3mA.
8. What is the hole current in the p region of the diode?
A. Ipp (x)=I-Inp (x)
B. Ipp (x)=I+Inp (x)
C. Ipp (x)=-I-Inp (x)
D. Ipp (x)=-I+Inp (x)
Answer: A
Clarification: The hole current in the p region is equal to the total current minus the minority electrons in the p region.
9. What does Inp represent?
A. Hole current in n region
B. Hole current in p region
C. Electron current in n region
D. Electron current in p region
Answer: D
Clarification: Inp constitutes of the electron current in the p region. It is the minority electron carrier in the p region.
10. Deep into the p side the current is a drift current Ipp of holes sustained by the small electric field in the semiconductor. Is the statement true or false?
A. True
B. False