A switching device including a first dielectric layer having a first top surface, two conductive features embedded in the first dielectric layer, each conductive feature having a second top surface that is substantially coplanar with the first top surface of the first dielectric layer, and a set of discrete islands of a low diffusion mobility metal between the two conductive features. The discrete islands of the low diffusion mobility metal may be either on the first top surface or embedded in the first dielectric layer. The electric conductivity across the two conductive features of the switching device increases when a prescribed voltage is applied to the two conductive features. A method of forming such a switching device is also provided.