Dear Ravil;
Thanks for your nice answers I am reading and searching the books,
My task is:
we have one piece of SOI(silicon on isolator), we made a wave guide with silicon on top of SiO2, SiO2 thickness is 340nm, this silicon is N-type, then we put two electrode on the waveguide, in this case we will have drift current in silicon right?(Delta is refer to this matter), on the same time we put the light in input of waveguide, so in conclusion we have light and drift current in our silicon, what I need is to find out the intraction between the light and electron or drift current which is availabe in this piece of silicon, I refer to book of Soref, he mention about formula but it is for P-N junction, in my case we just have N-type silicon. would you please help me to find an exact relation between light and electron in the silicon? again thanks for your answers