Atomic layer deposition of metal-oxide tunnel barriers using optimized oxidants

摘要

Metal oxide tunnel barrier layers for superconducting tunnel junctions are formed by atomic layer deposition. Both precursors include a metal (which may be the same metal or may be different). The first precursor is a metal alkoxide with oxygen bonded to the metal, and the second precursor is an oxygen-free metal precursor with an alkyl-reactive ligand such as a halogen or methyl group. The alkyl-reactive ligand reacts with the alkyl group of the alkoxide, forming a detached by-product and leaving a metal oxide monolayer. The temperature is selected to promote the reaction without causing the metal alkoxide to self-decompose. The oxygen in the alkoxide precursor is bonded to a metal before entering the chamber and remains bonded throughout the reaction that forms the monolayer. Therefore, the oxygen used in this process has no opportunity to oxidize the underlying superconducting electrode.

主权项

1. A method comprising:
forming a first superconducting layer on a substrate; exposing a surface of the first superconducting layer to a first precursor; and exposing the surface of the first superconducting layer to a second precursor;
wherein the first precursor comprises a metal alkoxide selected from the group consisting of zirconium(IV) t-butoxide and titanium(IV) n-butoxide;wherein the first superconducting layer comprises a metal selected such that the metal remains unoxidized by the metal alkoxide when the surface of the first superconducting layer is exposed to the second precursor;wherein the second precursor comprises an oxygen-free metal precursor having an alkyl-reactive ligand; andwherein the first precursor and the second precursor react to form a monolayer of metal oxide over the surface of the first superconducting layer.