Photodiode arrays and methods of fabrication are provided. One photodiode array includes a silicon wafer having a first surface and an opposite second surface. The photodiode array also includes a plurality of refilled conductive vias through the silicon wafer, wherein the refilled conductive vias have a doping type different than the doping type of the substrate, and an interface between the refilled conductive vias and the substrate form diode junctions. The photodiode array further includes a patterned doped layer on the first surface overlapping the refilled conductive vias, wherein the patterned doped layer defines an array of photodiodes.