Electroless atomic layer deposition
A method of electroless atomic layer deposition is described. The method electrolessly generates a layer of sacrificial material on a surface of a first material. The method adds doses of a solution of a second material to the substrate. The method performs a galvanic exchange reaction to oxidize away the layer of the sacrificial material and deposit a layer of the second material on the surface of the first material. The method can be repeated for a plurality of iterations in order to deposit a desired thickness of the second material on the surface of the first material.
1. A method of electroless atomic layer deposition, the method comprising:
electrolessly generating a layer of sacrificial material on a surface of a first material immersed in an electrolyte under conditions where the process is surface-limited, wherein a thickness of the layer of sacrificial material is on an order of an atomic thickness and the sacrificial material comprises hydrogen and the method of generating a layer of sacrificial material on a surface of a first material comprises bubbling a 0.01% to 2.5% mixture of hydrogen in a nonreactive gas into an electrolyte;
forming a layer of hydride on the surface of the first material as the layer of sacrificial material;
constraining an amount of hydride in the first material so that the number of moles of hydride does not exceed the amount of surface hydride;
adding doses of a solution of a second material; and
performing a surface-limited galvanic exchange reaction to oxidize away the layer of the sacrificial material and deposit a layer of the second material on the surface of the first material.
2. The method of claim 1 , wherein the electroless generating, adding, and performing the galvanic exchange are repeated for a plurality of iterations.
3. The method of claim 1 , wherein the electroless generation of the layer of the sacrificial material comprises forming the layer of the sacrificial material without using an external electrical power supply.
4. The method of claim 1 , wherein the galvanic exchange is performed in a liquid or a condensed phase with mobile atomic-scale species.
5. The method of claim 1 , wherein the first material is palladium and the second material is rhodium, wherein the solution of the second material contains rhodium(III) halide.
6. The method of claim 5 further comprising stirring under a mixture of dilute H 2 in the nonreactive gas at a pressure that is positive with respect to ambient atmosphere, wherein there is minimal gas flow during the addition of the solution and the stirring.
7. The method of claim 1 , wherein the second material is less easily oxidized than the first material.
8. The method of claim 1 , wherein the first material is one of metal powders, films, matrix-supported nanoparticles, metals patterned onto insulators, and 3D structured materials.