Space charge region of p-n junction diode

AI Thread Summary
The discussion centers on whether the mass action law, np = ni^2, holds true in the space charge region of a p-n junction diode. It is noted that for an unbiased junction without net carrier recombination or generation, this relationship is valid. However, many textbooks apply the depletion approximation, which assumes no carriers exist in the depletion region, focusing solely on ionized dopant concentrations. The law of the Junction is introduced, indicating that np = ni^2e^(qVa/kT) applies throughout the space charge region, with the mass action law being valid at zero applied voltage. Overall, the presence of carriers in the depletion region challenges traditional assumptions in semiconductor theory.
rkgjet
Messages
1
Reaction score
0
does np=ni^2 holds even the space charge region of a pn junction diode?
 
Engineering news on Phys.org
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.

400px-Pn-junction-equilibrium-1.png


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:

Thread 'How might electronics be different if AC voltage was 72V at 45 Hz?'

Hey guys. I have a question related to electricity and alternating current. Say an alien fictional society developed electricity, and settled on a standard like 73V AC current at 46 Hz. How would appliances be designed, and what impact would the lower frequency and voltage have on transformers, wiring, TVs, computers, LEDs, motors, and heating, assuming the laws of physics and technology are the same as on Earth?
View full post »

Thread 'What happens if shielded cable has a short to the shield?'

While I was rolling out a shielded cable, a though came to my mind - what happens to the current flow in the cable if there came a short between the wire and the shield in both ends of the cable? For simplicity, lets assume a 1-wire copper wire wrapped in an aluminum shield. The wire and the shield has the same cross section area. There are insulating material between them, and in both ends there is a short between them. My first thought, the total resistance of the cable would be reduced...
View full post »

Thread 'Why does the amperage go real high if there is a low voltage short?'

I used to be an HVAC technician. One time I had a service call in which there was no power to the thermostat. The thermostat did not have power because the fuse in the air handler was blown. The fuse in the air handler was blown because there was a low voltage short. The rubber coating on one of the thermostat wires was chewed off by a rodent. The exposed metal in the thermostat wire was touching the metal cabinet of the air handler. This was a low voltage short. This low voltage...
View full post »

Similar threads

Electron Current/movement in P-N junction under forward bias
Replies
3
Views
1K
I have a question about diodes and the PN junction
Replies
2
Views
2K
How do copper oxide solar cells work?
Replies
2
Views
1K
Why Don't We Add Potentials in a Forward-Biased PN Junction?
Replies
14
Views
2K
What Explains the Lack of Current in a PN Junction at Equilibrium?
Replies
3
Views
2K
Non uniformly distributed p-n junction related problem
Replies
3
Views
2K
What is the polarity of a Pn junction diode
Replies
42
Views
9K
Fundamentals of the PN Junction
Replies
12
Views
2K
Is my understanding of the working principle of a solar cell correct?
Replies
1
Views
1K
Help with the Key Points of Zener Breakdown and Avalanche Breakdown
Replies
1
Views
2K

Hot Threads

Recent Insights

Back
Top