I have looked all over in many textbooks and I cannot find a decent explanation of this. Most textbooks simply say that it is independent of applied bias because all of the minority carriers generated by thermal energy within a diffusion length of the depletion region will essentially get swept across the junction due to the field, regardless of the applied bias and the strength of the electric field. So, the drift current is essentially limited by the thermal generation rate of minority carriers in the neutral regions, and not by the field strength...however, it seems obvious that the field strength will affect the speed at which minority carriers drift, which will in turn affect the drift current, even if the number of charges that drift is the same. So, how do you explain this?? No textbook mentions that the drift speed changes depending on the bias. I considered that even though the speed at which the carreirs drift changes depending on the bias, the width of the depletion region is also changing, which could compensate, but when I work out the drift current I always end up with a bias dependence. I figure the drift current is of course J = qnv, where q is the change of a hole (or electron). I also assume that n, the number of minority carriers generated within a diffusion length of the depletion region is the same regardless of bias. So, the only thing that could change with respect the changes in bias is the speed, v, which is W/tdrift, but when I figure the velocity I always get a bias dependence. So, I am a bit lost as to why drift is independent of bias. Also, when the diode equation is derived only diffusion current is considered...but they call the reverse current Io in the resulting IV characteristics the 'reverse generation current', but reverse gen current is a DRIFT effect! So, how do you get drift characteristics out a derivation that only considers diffusion! This doesn't make much sense to me at all. I think the -Io term isn't really the reverse generation current.... Maybe someone can explain this nonsense to me. Thanks in advance.