A photodiode is provided according to various embodiments. In some embodiments, the photodiode includes a substrate and an active region. The active region is configured to receive light through the substrate. In such a configuration, the substrate not only participates in the photodiode operation acts as a light filter depending on the substrate material. In some embodiments, the active region may include solder balls that may be used to couple the photodiode to a printed circuit board. In some embodiments, the active region is coupled face-to-face with the printed circuit board.