Bissoy.com
Doctors Medicines MCQs Q&A

When a P-N junction diode is reversed biased the thickness of depletion layer-

When a P-N junction diode is reversed biased the thickness of depletion layer- Correct Answer Increases

Forward Bias:

[ alt="F1 P.Y Madhu 9.03.20 D 4" src="//storage.googleapis.com/tb-img/production/20/04/F1_P.Y_Madhu_9.03.20_D%204.png" style=" width: 307px; height: 291px;">

  • When forward biased, the applied voltage V of the battery mostly drops across the depletion region and the voltage drops across the p-side and n-side of the p-n junction is negligibly small.
  • In forward biasing the forward voltage opposes the potential barrier Vbi. As a result, the potential barrier height is reduced and the width of the depletion layer decreases.
  • As forward voltage is increased, at a particular value the depletion region becomes very much narrow such that a large number of majority charge carriers can cross the junction.

 

Reversed Bias:

[ alt="F1 P.Y Madhu 9.03.20 D 3" src="//storage.googleapis.com/tb-img/production/20/04/F1_P.Y_Madhu_9.03.20_D%203.png" style="width: 307px; height: 286px;">

  • The p-n Junction diode has one p node and one n node.
  • In the reverse bias, the negative voltage node is connected to the 'P' node. That means the positive voltage node is connected to the 'N' node.
  • When reverse biased, more charge carriers are depleted, resulting in the widening of the depletion region (thickness of depletion layer increases). 
  • This increases the opposing electric field for the diffusion carriers and does not allow them to cross the junction, offering a high resistance.

 

This can also be understood with the V-I characteristic of aP-N junction diode:

[ alt="F1 S.B Deepak 15.02.2020 D1" src="//storage.googleapis.com/tb-img/production/20/02/F1_S.B_Deepak_15.02.2020_D1.png" style="width: 578px; height: 399px;">

Related Questions

For transistor action (a) Base, emitter, and collector regions should have similar size and doping concentrations. (b) The base region must be very thin and lightly doped. (c) The emitter-base junction is forward biased and the base-collector junction is reverse biased. (d) Both the emitter-base junction as well as the base-collector junction are forward biased. Which one of the following pairs of statements is correct?
Consider the following statements regarding an N-P-N Bipolar Junction Transistor: 1. Emitter diode is forward biased and the collector diode is reverse biased 2. Emitter has many free electrons 3. Free electrons are injected into the base and pass through the collector 4. Depletion layers around junction J1 and J2 of BJT are widened. Which of the above statements are correct?
Assertion (A): A p-n junction diode with low junction depth can be used as a solar cell when illuminated by suitable light (wavelength) at the top thin layer above the junction. Reason (R): A p-n junction diode under no condition can be used as a solar cell. It can be used only as a light-emitting diode for optoelectronic applications.
A transistor is used in common emitter mode as an amplifier. Then a. The base-emitter junction is forward biased b. The base-emitter junction is reverse biased  c. The input signal is connected in series with the voltage applied to the base-emitter junction  d. The input signal is connected in series with the voltage applied to bias the base-collector junction Which of the following statement is true?
Some small cubes of same height 7 cm but variable length and width are put inside a large cuboid of height 21 cm. Length and width of cuboid is 32 cm and 24 cm, respectively. Small cubes are put such that cubes at the bottom most layer is of similar base area; second layer contains all the cubes of similar base area and third layer have all the cubes of similar base area. Which of the following statement(s) given below is / are TRUE? A: If side of each small cubes at bottom most layer is 8 cm, then maximum number of small cubes that can be put at bottom most layer is 12. B: If maximum of 48 cubes can be put at second layer, then side of each cube at second layer is 6 cm. C: If side of each small cubes at third layer is 1.6 cm, then maximum number of small cubes that can be put at third layer is 300.
Which of the following is the correct match based on the application of diodes? (considering general trends) (a) Zener diode -- Reverse biased (b) Photodiode - Forward biased (c) Half wave Rectifier - Both Forward and reversed biased
When the p-n junction diode is reversed biased, the width of the depletion region __________
In a pnp-BJT, when the E-B junction is forward biased and no voltage is applied across C-B junction, what happens to the width of the depletion region in the E-B junction?
A PN junction diode with 100Ω resistor is forward biased such that 100A current flows. If voltage across this combination is instantaneously reversed to 10V at t=0, the reverse current that flows through diode at t=0 is?
When reverse biased, the width of depletion layer in a PN junction diode: