1. A memory device, comprising: a first electrode; a chalcogenide glass material formed over said first electrode; a tin chalcogenide material formed over said chalcogenide glass material; a first silver material formed over said tin chalcogenide material; a second silver material formed below said tin chalcogenide material; and a second electrode formed over said first electrode, said chalcogenide glass material, said tin chalcogenide material, said first silver material and said second silver material.