In some embodiments, the present disclosure relates to an integrated chip having a photodetector arranged within a semiconductor substrate having a first doping type. One or more dielectric materials are disposed within a trench defined by interior surfaces of the semiconductor substrate. A doped epitaxial material arranged within the trench at a location laterally between the one or more dielectric materials and the photodetector. The doped epitaxial material has a second doping type that is different than the first doping type.