In some embodiments, the present disclosure relates to a method of forming an integrated chip. The method includes doping a substrate to form a first well region having a first doping type, and selectively etching an upper surface of the substrate to define a trench extending into the first well region. The trench is filled with one or more dielectric materials. The substrate is implanted to form a first photodiode region within the substrate. The first photodiode region is separated from the trench by the first well region. A first part of the one or more dielectric materials is removed from within the trench to expose a sidewall of the substrate that defines the trench and that is proximate to the first photodiode region. A doped epitaxial material having the first doping type is formed along the sidewall of the substrate.