1. A method for forming a selector device for a two-terminal memory device, comprising: providing a first layer structure comprising a first metal material; providing a layer of selector material in contact with the first layer structure; and providing a second layer structure comprising a second metal material and in contact with the layer of the selector material, wherein: the first metal material is configured to provide conductive ions to the selector material in response to a voltage applied across the first layer structure and the second layer structure, the selector material is configured to allow the conductive ions to permeate within the layer of selector material and form a conductive filament across the selector material in response to the voltage applied across the first layer structure and the second layer structure, wherein the selector material is configured to facilitate a break in electrical continuity of the conductive filament in response to a reduction in magnitude of the voltage to a reduced voltage, greater than zero, and having a same polarity as the voltage, the first layer structure, the layer of selector material, and the second layer structure form the selector device, and the selector device is disposed in electrical series with the two-terminal memory device.