A CMOS image sensor cell includes a semiconductor active region of first conductivity type having a surface thereon and a P-N junction photodiode in the active region. A drive transistor is also provided in the semiconductor active region. The drive transistor has a gate electrode that is configured to receive charge generated in the P-N junction photodiode during an image capture operation (i.e., during capture of photons received from an image). This drive transistor has a gate electrode and a contoured channel region extending underneath the gate electrode. The contoured channel region has an effective channel length greater than a length of the gate electrode.