- #1
rkgjet
- 1
- 0
does np=ni^2 holds even the space charge region of a pn junction diode?
Space charge region of p-n junction diode
- Thread starter rkgjet
- Start date
-
- Tags
- Charge Diode Junction P-n junction Space
In summary, the experts discuss whether the equation np=n_i^2 holds true for the space charge region of a pn junction diode. Some argue that it is valid for an unbiased junction with no carrier recombination or generation, while others suggest using the depletion approximation which assumes no carriers in the region. The graph shown in the conversation supports the idea that carrier concentrations do not go to zero in the depletion region. They also mention a law known as the "law of the Junction" which is valid throughout the space charge region and is recovered for V_a=0.
- #2
bob012345
Gold Member
- 2,066
- 891
For an unbiased junction with no net carrier recombination or generation I believe it does however most books use the depletion approximation where they assume there are no carriers in the space charge or depletion region and only the ionized donor and acceptor dopant concentrations matter. This graph shows the carrier concentrations to not go to zero in the depletion region.
There is something called the law of the Junction which goes as ##np=n_i^2e^{qV_a/kT}## where ##V_a## is the applied voltage. This is valid throughout the space charge region. For ##V_a=0## the mass action law ##np = n_i^2## is recovered.
https://inst.eecs.berkeley.edu/~ee130/fa13/pnjunctions.pdf
There is something called the law of the Junction which goes as ##np=n_i^2e^{qV_a/kT}## where ##V_a## is the applied voltage. This is valid throughout the space charge region. For ##V_a=0## the mass action law ##np = n_i^2## is recovered.
https://inst.eecs.berkeley.edu/~ee130/fa13/pnjunctions.pdf
Last edited:
1. What is the space charge region of a p-n junction diode?
The space charge region, also known as the depletion region, is the area near the junction of a p-n junction diode where there is a lack of free charge carriers due to the diffusion of majority carriers from one side to the other. This creates a region with a net charge, known as the space charge region.
2. How does the space charge region affect the behavior of a p-n junction diode?
The space charge region plays a crucial role in the functioning of a p-n junction diode. It acts as a barrier to the flow of current in the reverse bias direction, preventing the majority carriers from crossing the junction. In the forward bias direction, the space charge region becomes thinner, allowing for the flow of majority carriers and creating a low resistance path for current.
3. What factors influence the width of the space charge region?
The width of the space charge region is influenced by the doping concentrations of the p and n regions, as well as the applied voltage across the diode. Higher doping concentrations result in a narrower space charge region, while a higher applied voltage will widen the space charge region.
4. How does the space charge region change with temperature?
The width of the space charge region is directly proportional to temperature. As the temperature increases, the diffusion of majority carriers also increases, resulting in a wider space charge region. This can lead to a decrease in the diode's overall performance.
5. Can the space charge region be eliminated in a p-n junction diode?
No, the space charge region is an inherent part of the design of a p-n junction diode. However, its effects can be minimized by carefully selecting the doping concentrations and operating conditions of the diode.
Similar threads
-
Electrical Engineering
-
Electrical Engineering
-
Electrical Engineering
-
Electrical Engineering
-
Electrical Engineering
-
Electrical Engineering
-
Electrical Engineering
-
Electrical Engineering
-
Classical Physics