1. A memory cell comprising: a first conductive layer operable as an electrode; a second conductive layer operable as an electrode; a semiconductor layer between the first conductive layer and the second conductive layer; and a defect access layer between the first conductive layer and the semiconductor layer; wherein a work function of the first conductive layer is higher than a work function of the second conductive layer; and wherein the defect access layer increases an effective work function of the first conductive layer.