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Photodiode shunt resistance and Photodiode layout question



Jan 1, 1970
Hopefully this is the right group for these two questions:

1) For a photodiode, the series resistance is due to the contact
resistance (as one factor), but what is the source of a photodiode
shunt resistance? Is it simply due to the inherent resistence of the
junction to the current flow due to diffusion in photovoltaic mode and
drift currents in photoconductive mode?

2) Also, in regards to a layout of a basic PN junction photodiode, if
you have an N-Well in a P-epi photodiode, with P+ contacts around the
N-Well, and N+ contacts in the N-well, the depletion region extends
mostly into the P-epi (as it is lighter doped). However, does it
matter whether the N+ contacts cover the entire N-well or are just
placed at its edges?