So I was shinning some Cree leds onto a photodiode and measuring the photoc urrent. Here?s a plot (opamp bias current ~20pA subtracted from data.)
Below about 1mA of LED bias current the photo current increases as the 3/2 power of the led current. Which was totally unexpected! (I expected linea r.) I?m making up a hand-waving explanation that?s got a non-radiative rec ombination channel. And then observing that for radiatvie recombination, i t?s not only the number of charge carriers at the boundary.. but they als o have to find a ?dancing partner? on the other side. So some kind of factor that has do with hole and electron wave function overlap. And for two dimensions that could go as the square root of the number density. (I think.)
Does that make sense? Is this known?
Thanks George H.