A semiconductor structure includes a substrate; at least one mask layer spaced apart from the substrate in a first direction; a first semiconductor region of a first conductivity type between the substrate and the at least one mask layer; a second semiconductor region of a second conductivity type on the at least one mask layer; and a third semiconductor region of the first conductivity type on the first semiconductor region. The third semiconductor region may contact the second semiconductor region to form a PN-junction structure in a second direction different from the first direction. The semiconductor structure may be applied to vertical power devices and may be capable of increasing withstand voltage performance and lowering an on-resistance.