The present invention is directed to a memory device that includes an array of memory cells. Each of the memory cells includes a memory element connected to a two-terminal selector element. The two-terminal selector element includes a first electrode and a second electrode with a switching layer interposed therebetween. The switching layer includes a plurality of metal-rich clusters embedded in a nominally insulating matrix. One or more conductive paths are formed in the switching layer when an applied voltage to the memory cell exceeds a threshold level. Each of the memory cells may further include an intermediate electrode interposed between the memory element and the two-terminal selector element. The two-terminal selector element may further include a third electrode formed between the first electrode and the switching layer, and a fourth electrode formed between the second electrode and the switching layer.