What is a typical diode's ideality factor?
I am currently taking a semiconductor class and we recently did an experiment to measure the ideality factor for two different diodes, one of germanium and one of silicon composition. The experiment found the silicon diode to have an ideality factor of 1 and the germanium to have a factor of 1.4. According to my professor the ideality factor is indicative of the type of charge carrier recombination that is occurring inside of the diode based on the following chart.



In order to calculate n, I measured and graphed the I-V (V being the voltage across the diode not the applied voltage) characteristics of the diodes and found the slope as such:

Then knowing this relationship where e is the charge of an electron, T is temperature and K is the Boltzman constant and I naught is the inverse saturation current:



I find the slope of the graph to be:



Solving for n yields a 1. 

I think that answers 3 out of 5 of your questions.

I hope all of that helped!