An image sensor semiconductor device includes a first photodiode disposed in a semiconductor substrate and configured to generate charges in response to radiation, a first transistor disposed adjacent to the first photodiode, a floating diffusion region configured to store the generated charges, a reset transistor configured to reset the floating diffusion region, and a second transistor disposed over the substrate between the first photodiode and the reset transistor. The first transistor and the second transistor are configured to generate a first electric field and a second electric field, respectively, to move the charges generated by the first photodiode to the floating diffusion region.