A back-illuminated image sensor, comprising: a sensor layer of a first conductivity type having a frontside and a backside opposite the frontside; an insulating layer disposed on the backside of the sensor layer; a circuit layer electrically connected to the sensor layer and adjacent to the frontside of the sensor layer; one or more frontside regions (726, 728, 730) of a second conductivity type formed in at least a portion of the frontside of the sensor layer; a backside region of the second conductivity type formed in the backside of the sensor layer; a plurality of frontside photodetectors (718f, 720f, 722f) of the first conductivity type for converting light incident on the backside of the sensor layer into photo-generated charges, wherein the plurality of frontside photodetectors is disposed in the sensor layer and adjacent to the frontside; wherein the one or more frontside regions (726, 728, 730) of the second conductivity type are formed over each frontside photodetector (718f, 720f, 722f); the back-illuminated image sensor further comprising: a discrete plurality of backside photodetectors (718b, 720b, 722b) of the first conductivity type separate from the plurality of frontside photodetectors for converting light incident on the backside of the sensor layer into photo-generated charges, wherein the plurality of backside photodetectors is disposed in the sensor layer and contiguous to portions of the backside region of the second conductivity type; a voltage terminal electrically connected to at least one frontside region of the second conductivity type for biasing the one or more frontside regions to a voltage, wherein each frontside photodetector is paired with a respective backside photodetector to form photodetector pairs and wherein one or more connecting regions (742, 744) of the second conductivity type are disposed in respective portions of the sensor layer between the one or more frontside regions and the backside region of the second conductivity type and between each photodetector pair for electrically connecting the frontside and backside regions to one another. a sensor layer of a first conductivity type having a frontside and a backside opposite the frontside; an insulating layer disposed on the backside of the sensor layer; a circuit layer electrically connected to the sensor layer and adjacent to the frontside of the sensor layer; one or more frontside regions (726, 728, 730) of a second conductivity type formed in at least a portion of the frontside of the sensor layer; a backside region of the second conductivity type formed in the backside of the sensor layer; a plurality of frontside photodetectors (718f, 720f, 722f) of the first conductivity type for converting light incident on the backside of the sensor layer into photo-generated charges, wherein the plurality of frontside photodetectors is disposed in the sensor layer and adjacent to the frontside; a discrete plurality of backside photodetectors (718b, 720b, 722b) of the first conductivity type separate from the plurality of frontside photodetectors for converting light incident on the backside of the sensor layer into photo-generated charges, wherein the plurality of backside photodetectors is disposed in the sensor layer and contiguous to portions of the backside region of the second conductivity type; a voltage terminal electrically connected to at least one frontside region of the second conductivity type for biasing the one or more frontside regions to a voltage, wherein each frontside photodetector is paired with a respective backside photodetector to form photodetector pairs and wherein one or more connecting regions (742, 744) of the second conductivity type are disposed in respective portions of the sensor layer between the one or more frontside regions and the backside region of the second conductivity type and between each photodetector pair for electrically connecting the frontside and backside regions to one another.