Hi,

my first suggestion is to consult the book by S.M. Sze (Physics of Semiconducting Devices - 2nd edition, J.Wiley 1981, page 264 etc.).

The problem with so called "ideal" diode equation is that it is just an analytical approximation to the true non-linear problem that can be only solved numerically. Some of the assumptions (such as "image force" concept) are highly questionable if not directly wrong.

However, I guess that as a first order approximation the equation (and the corresponding empirical "ideality factor") can be used.

The effect of illumination is re-distribution of the electron-hole densities within the optical penetration depth. Also this problem is probably best solved by a proper numerical simulation (see US patent 5 627 479, May 6, 1997).

I hope this helps on the way

With best regards

Petr