A multi-pixel detector of an image sensor is described. The multi-pixel detector includes a first photodiode region disposed within a semiconductor substrate to form a first pixel, a second photodiode region disposed within the semiconductor substrate to form a second pixel adjacent to the first pixel, and a partial isolation structure extending from a first side of the semiconductor substrate towards a second side of the semiconductor substrate between the first photodiode region and the second photodiode region. A length of a lateral portion of the partial isolation structure between the first photodiode region and the second photodiode region is less than a lateral length of the first photodiode region.