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