We have been looking at P-N junction diodes in our lab session this week and investigating the current through the circuit and how this relates to the Voltage. We are using the approximation: I = (I0)*exp(qV/kT) We measured the voltage and the current for a few different voltages and this could be plotted into a graph. A regression analysis gave the reverse saturation current as I0 = 3.2 x 10^-6 A, and the effective charge carrier charge as q = 4.78 x 10^-21 C. The diode being used is the 1N4148 junction diode. Im trying to understand why the carrier charge is not equal to 1.6*10^-19 C. We were told that it has something to do with the data-sheet for this diode. But so far Im not sure what on the sheet I should be looking for and even how this would related to solving this problem. Any help would be appreciated, Thanks Ben.