1. A memory device having a crossbar array, the memory device comprising: a first array of first electrodes extending along a first direction; a second array of second electrodes extending along a second direction, each second electrode comprising a polycrystalline silicon-germanium material layer, wherein an insulating layer separates polycrystalline silicon-germanium material layer of second electrodes of the second array of second electrodes; and a non-crystalline silicon structure provided between the first electrode and the second electrode at an intersection defined by the first array and the second array, wherein the first array of the first electrodes are provided over the non-crystalline silicon structure, and the second array of the second electrodes and the insulating layer are rovided below the non-crystalline silicon structure, and wherein each intersection of the first array and the second array defines a two-terminal resistive memory cell.