A pixel cell includes a nitrogen-implanted region at a semiconductor material-gate oxide proximate interface located in a region above a photodiode. The pixel cell is further devoid of implanted nitrogen in channel regions of a plurality of pixel transistors. Thus, Si—N bonds are formed at the semiconductor material-gate oxide interface in the region above the photodiode, while the channel regions are protected from nitrogen implantation at the semiconductor material-gate oxide interface. Methods of forming the pixel cell are also described.