An electrical device includes a first layer, a second layer and an intrinsic layer. The first layer is of a first conductivity type, wherein the second layer is of a second conductivity type opposite to the first conductivity type. The intrinsic layer is arranged between the first and the second layer and has a reduced thickness at at least one portion. An area of the at least one portion is less than 50% of an active area in which the first and second layer face each other.