Disclosed is a method for the fabrication of a correlated electron material (CEM) device comprising: forming a layer of a conductive substrate on a substrate; forming a layer of a correlated electron material on the layer of conductive substrate; forming a layer of a conductive overlay on the layer of correlated electron material; patterning these layers to form a stack comprising a conductive substrate, a CEM layer and a conductive overlay, on the substrate; forming a cover layer of an insulating material over the stack; and patterning the cover layer wherein: the patterning of the cover layer comprises etching a trench in the cover layer whereby to expose the conductive overlay; and the method further comprises treating the exposed conductive overlay to remove an oxidation layer there from.