The present disclosure, in some embodiments, relates to an integrated chip. The integrated chip includes a photodetector arranged within a substrate. The substrate has surfaces defining one or more protrusions arranged along a first side of the substrate over the photodetector. One or more isolation structures are arranged within one or more trenches defined by sidewalls of the substrate arranged on opposing sides of the photodetector. The one or more trenches extend from the first side of the substrate to within the substrate. The one or more isolation structures respectively include a reflective medium configured to reflect electromagnetic radiation.