Does the diode ideality factor can be lesser than 1? or very close to 1?

enter image description here

ID and VD are the diode current and voltage, respectively

q is the charge on the electron

n is the ideality factor

k is Boltzmann’s constant

T is temperature in Kelvin

  • \$\begingroup\$ Where did the equation come from? What are D, S, q, VD, n, k and T? \$\endgroup\$
    – Transistor
    Aug 6, 2018 at 13:41
  • 1
    \$\begingroup\$ @Transistor Looks like the Shockley Diode Equation... or was that something you wanted the OG to figure out? Lol woops \$\endgroup\$
    – user103380
    Aug 6, 2018 at 14:18

1 Answer 1


The ideality factor adjusts the original Shockley diode equation to fit non-Germanium diodes more closely. There's also a series resistance term.

Equation 3.13 from the original 1950 paper from Bell System Technical Journal:

enter image description here

The factor was added a few years later in a fascinating paper on radioactive p-n junction power sources.

enter image description here

With silicon diodes the ideality factor is closer to 2 than 1. It can be higher than 2. A diode-connected silicon transistor operated at reasonable currents has an ideality factor close to 1.

I don't think it is ever less than 1 for a real diode, but that may not be correct.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.