A semiconductor device contains a photodiode which includes a buried collection region formed by a bandgap well to vertically confine photo-generated minority carriers. the bandgap well has the same conductivity as the semiconductor material immediately above and below the bandgap well. A net average doping density in the bandgap well is at least a factor of ten less than net average doping densities immediately above and below the bandgap well. A node of the photodiode, either the anode or the cathode, is connected to the buried collection region to collect the minority carriers, the polarity of the node matches the polarity of the minority carriers. The photodiode node connected to the buried collection region occupies less lateral area than the lateral area of the buried collection region.