Why does Zener breakdown occure and why is it happeing?

  • Thread starter nazia_f
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In summary, Zener diode operation depends on the heavy doping of its p-n junction. This allows electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material. This tunneling is the transport of valence band electrons into the empty conduction band states. The reduced barrier between these bands and high electric fields from the dopings can lead to Zener breakdown, which is a sharp change in the diode's characteristics. This is because the strong electric field in the junction region can disrupt the bonding forces within the atom, generating carriers. The breakdown voltage, Zener voltage, and peak reverse voltage are all terms that refer to the same thing. To understand this further, one would
  • #1
nazia_f
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I was reading Zener diode topic from Boylestad's book and there was a line that I didn't quite understand. It states -
"Zener breakdown will contribute to the sharp change in the characteristics because there is a strong electric field in the region of the junction that can disrupt the bonding forces within the atom and "generate" carriers."
What does it actually mean? What I want to know is how a strong electric field is being created and how this electric field is disrupting the bonding forces within atom? How are carrier being generated? Are they majority carrier or minority carrier?
I want to know the internal mechanism of the occurrence of Zener breakdown.
Could anyone please help me out?
Also, Zener potential, Breakdown voltage and Peak inverse/reverse voltage - do these three terms refer to the same thing?
 
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  • #2
Wikipedia: "The Zener diode's operation depends on the heavy doping of its p-n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material. In the atomic scale, this tunneling corresponds to the transport of valence band electrons into the empty conduction band states; as a result of the reduced barrier between these bands and high electric fields that are induced due to the relatively high levels of dopings on both sides."

If you want to understand this further you need to pursue a course in solid state physics. Tunneling itself is a failry recent discovery and the theory lagged the discovery by quite a while.

Breakdown voltage, zener voltage and peak reverse voltage are nominally the same.
 
  • #3
Thank you for helping me. I am going to study it a bit more.
 

1. Why does Zener breakdown occur?

Zener breakdown occurs because of the high electric field that is applied to a reverse-biased Zener diode. This high electric field causes a phenomenon known as avalanche breakdown, where free electrons are accelerated to high energies and collide with atoms, releasing more free electrons. This creates a self-sustaining chain reaction, leading to a large current flow and breakdown of the diode.

2. What is the difference between Zener breakdown and avalanche breakdown?

While both Zener breakdown and avalanche breakdown occur due to high electric fields in a reverse-biased diode, they differ in their mechanisms. Zener breakdown occurs in heavily doped diodes, where the depletion region is narrow and electric fields are high. In avalanche breakdown, the depletion region is wider and the electric field is spread out, leading to a more gradual increase in current.

3. Can Zener breakdown be controlled?

Yes, Zener breakdown can be controlled by adjusting the doping level of the diode. A higher doping level results in a narrower depletion region and therefore a lower breakdown voltage. This allows for the design of Zener diodes with specific breakdown voltages for different applications.

4. What causes a Zener diode to breakdown at a specific voltage?

The specific breakdown voltage of a Zener diode is determined by its doping level and the width of the depletion region. A higher doping level results in a lower breakdown voltage, as there are more free electrons available to participate in the avalanche breakdown process. The width of the depletion region also plays a role, as a narrower depletion region leads to a higher electric field and therefore a lower breakdown voltage.

5. Why is Zener breakdown important?

Zener breakdown is important because it allows for the use of Zener diodes as voltage regulators. When operated in the breakdown region, Zener diodes maintain a constant voltage across their terminals, even when the input voltage changes. This makes them useful in electronic circuits to provide a stable reference voltage for other components to operate from.

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