# Diode Ideality Factor

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

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

• Where did the equation come from? What are D, S, q, VD, n, k and T? – Transistor Aug 6 '18 at 13:41
• @Transistor Looks like the Shockley Diode Equation... or was that something you wanted the OG to figure out? Lol woops – KingDuken Aug 6 '18 at 14:18

## 1 Answer

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:

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

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.