From my understanding, even if the frequency of a photon is above the threshold frequency, it is not necessary that an electron gets ejected as the photon may have been absorbed by a metal atom multiple layers below the surface, and thus the ejected electron could then get trapped by a metal atom above it.
However, if so then it appears that photoelectric current should have some dependence on the frequency (which it doesn't in my knowledge). This is because the higher KE imparted by the increased frequency would make the probability of electron getting trapped less than before, and thus higher frequency would mean more electrons than before get ejected which implies a greater saturation photocurrent.
So is it just that the fraction of electrons that get trapped instead of just having reduced KE is so low (why?) that it's negligible? Or are one of my assumptions wrong
electrons can get trapped by metal atoms above it
the mechanism by which they get trapped is such that higher KE won't even be a factor, irrespective of KE essentially all that were getting trapped before will still get trapped