Concepts Of Physics MCQ Edition [Volume 2]
- Exam
- Concepts Of Physics MCQ Edition [Volume 2]
- Subject
- Physics
- Chapter
- Semiconductors and Semiconductor Devices
Concepts Of Physics MCQ Edition [Volume 2] · Physics · Semiconductors and Semiconductor Devices
For a p - n junction having open ends,
For a - junction having open ends,
Options
- Aholes and conduction electrons systematically travel from the -side to the -side and from the -side to the -side, respectively
- Ba constant electric field exists near the junction
- Cno net transfer of charge occurs between the two sides
- Dcharge carriers possess no systematic motion
Correct answer
C. no net transfer of charge occurs between the two sides
Step-by-step solution
In a - junction with open ends (unbiased condition), the system is in a steady state of equilibrium.
Due to the concentration gradient, majority carriers (holes from the -side and electrons from the -side) diffuse across the junction. This leaves behind uncovered, immobile positive and negative ions, creating a depletion region.
These immobile ions establish a built-in electric field near the junction directed from the -side to the -side. In the steady state, this electric field remains constant in time.
The built-in electric field causes a drift current of minority carriers that exactly balances the diffusion current of majority carriers. As a result, the net current across the junction is zero, meaning there is no net transfer of charge between the two sides.
Although individual charge carriers possess systematic motion (drift and diffusion), their effects cancel out macroscopically, resulting in zero net systematic transfer of charge. Thus, a constant electric field exists near the junction and no net transfer of charge occurs.
Due to the concentration gradient, majority carriers (holes from the -side and electrons from the -side) diffuse across the junction. This leaves behind uncovered, immobile positive and negative ions, creating a depletion region.
These immobile ions establish a built-in electric field near the junction directed from the -side to the -side. In the steady state, this electric field remains constant in time.
The built-in electric field causes a drift current of minority carriers that exactly balances the diffusion current of majority carriers. As a result, the net current across the junction is zero, meaning there is no net transfer of charge between the two sides.
Although individual charge carriers possess systematic motion (drift and diffusion), their effects cancel out macroscopically, resulting in zero net systematic transfer of charge. Thus, a constant electric field exists near the junction and no net transfer of charge occurs.