A semiconductor device includes a substrate including a first impurity diffusion region having a first doping concentration and at least one second impurity diffusion region having a second doping concentration different from the first doping concentration, the at least one second impurity region being surrounded by the first impurity diffusion region; at least one electrode facing the first impurity diffusion region and the at least one second impurity diffusion region; and at least one insulating layer between the first impurity diffusion region and the at least one electrode, and between the at least one second impurity diffusion region and the at least one electrode.