A semiconductor device includes a substrate of a first conductivity type, a first doped region of a second conductivity type, at least one second doped region of the first conductivity type, a third doped region of the second conductivity type, a gate structure, and at least one contact. The first and the second doped regions are configured in the substrate, and each second doped region is surrounded by the first doped region. The third doped region is configured in the substrate outside of the first doped region. The gate structure is disposed on the substrate between the first and third doped regions. The contact is disposed on the substrate. Each contact connects, in a direction parallel to the gate structure, the first and second doped regions alternately.