A vertical color filter sensor group formed on a substrate (preferably a semiconductor substrate) and including at least two vertically stacked, photosensitive sensors, and an array of such sensor groups. In some embodiments, a carrier-collection element of at least one sensor of the group has substantially larger area, projected in a plane perpendicular to a normal axis defined by a top surface of a top sensor of the group, than does each minimum-sized carrier-collection element of the group. In some embodiments, the array includes at least two sensor groups that share at least one carrier-collection element. Optionally, the sensor group includes at least one filter positioned relative to the sensors such that radiation that has propagated through or reflected from the filter will propagate into at least one sensor of the group.