Barrier design for steering elements

摘要

Steering elements suitable for memory device applications can have low leakage currents at low voltages to reduce sneak current paths for non selected devices, and high leakage currents at high voltages to minimize voltage drops during device switching. In some embodiments, the steering element can include a first electrode, a second electrode, and a graded dielectric layer sandwiched between the two electrodes. The graded dielectric layer can include a varied composition from the first electrode to the second electrode. Graded energy level at the top and/or at the bottom of the band gap, which can be a result of the graded dielectric layer composition, and/or the work function of the electrodes can be configured to suppress tunneling and thermionic current in an off-state of the steering element and/or to maximize a ratio of the tunneling and thermionic currents in an on-state and in an off-state of the steering element.

主权项

1. A steering element comprising
a first electrode; a second electrode; and a dielectric layer disposed between the first and the second electrodes,
wherein the dielectric layer has a conduction band and a valence band and a band gap between the conduction band and the valence band,wherein the conduction band has a conduction band minimum energy level,wherein the conduction band minimum energy level increases from the first electrode to a first point positioned within the dielectric layer,wherein the conduction band minimum energy level decreases from a second point positioned with the dielectric layer to the second electrode, andwherein the dielectric layer comprises a first set of elements and a second set of elements,wherein the first set of elements comprises strontium (Sr) and titanium (Ti) and wherein a ratio of strontium to titanium in the first set of elements is constant throughout the dielectric layer,wherein the second set of elements comprises barium (Ba) and zirconium (Zr) and wherein a ratio of barium to zirconium in the second set of elements is constant throughout the dielectric layer,wherein a ratio of the first set of elements to the second set varies from the first electrode to the first point causing the conduction band minimum energy level to increase from the first electrode to the first point, andwherein a ratio of the first set of elements to the second set varies from the second electrode to the second point causing the conduction band minimum energy level to decrease from the second point to the second electrode.