Diode built in electric field

Discussion in 'Homework Help' started by Ledwardz, Apr 7, 2012.

  1. Ledwardz

    Thread Starter Member

    Oct 31, 2010

    The question asks me to find out the built in electric field of a diode using my capacitance voltage relationship and compare this to the diode turn on voltage.

    Okay, so i have my tun on voltage and my graph which is the capacitance voltage relationship.

    Looking around on the internet i find the big ass equation using doping concentrations etc but the question does not give me any of these or tell me the material of the diode sooooo i assume this is not the way to do it.

    I also find out that the energy stored in the capacitor is stored in an electric field given by W = 0.5CV^2 but it can't be this easy can it?

    I should also mention i found the internal capacitance of the diode using the capacitance voltage relationship.

    This would enable me to find the built in electric field at the diodes turn on voltage which is 0.38V but what about its internal electric field because the voltage would be zero and hence the electric field is zero .....

    Now i think about it, i have the IV curves for different light intensitys including one in the dark. Could i use this to find out the inbuilt voltage and substitute it into the equation?

    Thanks for any help and your time, Lee.