A back-illuminated image sensor includes a sensor layer of a first conductivity type having a frontside and a backside opposite the frontside. An insulating layer is disposed over the backside. A circuit layer is formed adjacent to the frontside such that the sensor layer is positioned between the circuit layer and the insulating layer. One or more frontside regions of a second conductivity type are formed in at least a portion of the frontside of the sensor layer. A backside region of the second conductivity type is formed in the backside of the sensor layer. A plurality of frontside photodetectors of the first conductivity type is disposed in the sensor layer. A distinct plurality of backside photodetectors of the first conductivity type separate from the plurality of frontside photodetectors is formed in the sensor layer contiguous to portions of the backside region of the second conductivity type.