Maximum Built-In Voltage of a PN junction

In summary, the conversation discusses the calculation of the built-in voltage of a p-n junction and the maximum built-in voltage before the semiconductor becomes degenerate. It is mentioned that the calculation is not as simple as taking a derivative and setting it to zero, and a link is provided for the standard formula for the built-in voltage. There is also a clarification about the formula referring to a junction, not a semiconductor.
  • #1
Corwin_S
11
1
Hi,

I'm familiar with the expression for calculating the built-in voltage of a p-n junction. How can I find the maximum built-in voltage before the semiconductor becomes degenerate (i.e., a bad metal) if I only know the material and the intrinsic carrier concentration at a given temperature?

Unfortunately it is not as simple as taking a derivative and setting it to zero, because the derivative of the built-in voltage expression goes as 1/x.

Cheers
 
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  • #2
Can you define the "built-in voltage of a semiconductor"?
 
  • #3
Absolutely, look at 4.2.3 of this link for the standard formula:
http://ecee.colorado.edu/~bart/book/book/chapter4/ch4_2.htm
 
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Likes nasu
  • #4
The formula (and the figure) refers to a junction and not to a semiconductor. This is what I found confusing.
Thank you for clarification.
 
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Likes Corwin_S
  • #5
nasu said:
The formula (and the figure) refers to a junction and not to a semiconductor. This is what I found confusing.
Thank you for clarification.
I see! Indeed that was a mistake.
 

Related to Maximum Built-In Voltage of a PN junction

What is the maximum built-in voltage of a PN junction?

The maximum built-in voltage of a PN junction is the maximum potential difference that can be generated across the depletion region of the junction under equilibrium conditions. This voltage is dependent on the doping levels of the p and n regions of the junction, and is typically between 0.5V to 1V for silicon PN junctions.

How does the maximum built-in voltage affect the performance of a PN junction?

The maximum built-in voltage plays a crucial role in determining the characteristics and performance of a PN junction. A higher built-in voltage can result in a larger depletion region, which can lead to a lower breakdown voltage and increased reverse leakage current. On the other hand, a lower built-in voltage can result in a smaller depletion region, which can lead to a higher breakdown voltage and lower reverse leakage current.

What factors can affect the maximum built-in voltage of a PN junction?

The maximum built-in voltage of a PN junction is primarily determined by the doping concentrations of the p and n regions. Other factors that can affect the built-in voltage include the temperature, the type of semiconductor material, and the presence of impurities or defects in the junction.

How is the maximum built-in voltage calculated?

The maximum built-in voltage can be calculated using the following formula: Vbi = (kT/q) * ln(Nd/Ni), where k is the Boltzmann constant, T is the temperature in Kelvin, q is the charge of an electron, Nd is the donor impurity concentration, and Ni is the intrinsic carrier concentration of the semiconductor material.

What are some applications of the maximum built-in voltage of a PN junction?

The maximum built-in voltage plays a crucial role in various electronic devices and circuits, such as diodes, transistors, and solar cells. It also helps in determining the breakdown voltage and operating range of these devices, making it an essential parameter in their design and performance.

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