Synthesis of metal oxide surfaces and interfaces with crystallographic control using solid-liquid-vapor etching and vapor-liquid-solid growth

Patent metadata

Field	Value
Publication number	US-10312081-B2
Application number	US-201615370041-A
Country	US
Kind code	B2
Filing date	Dec 6, 2016
Priority date	Jul 15, 2016
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

The present invention provides integrated nanostructures comprising a single-crystalline matrix of a material A containing aligned, single-crystalline nanowires of a material B, with well-defined crystallographic interfaces are disclosed. The nanocomposite is fabricated by utilizing metal nanodroplets in two subsequent catalytic steps: solid-liquid-vapor etching, followed by vapor-liquid-solid growth. The first etching step produces pores, or “negative nanowires” within a single-crystalline matrix, which share a unique crystallographic direction, and are therefore aligned with respect to one another. Further, since they are contained within a single, crystalline, matrix, their size and spacing can be controlled by their interacting strain fields, and the array is easily manipulated as a single entity—addressing a great challenge to the integration of freestanding nanowires into functional materials. In the second, growth, step, the same metal nanoparticles are used to fill the pores with single-crystalline nanowires, which similarly to the negative nanowires have unique growth directions, and well-defined sizes and spacings. The two parts of this composite behave synergistically, since this nanowire-filled matrix contains a dense array of well-defined crystallographic interfaces, in which both the matrix and nanowire materials convey functionality to the material. The material of either one of these components may be chosen from a vast library of any material able to form a eutectic alloy with the metal in question, including but not limited to every material thus far grown in nanowire form using the ubiquitous vapor-liquid-solid approach. This has profound implications for the fabrication of any material intended to contain a functional interface, since high interfacial areas and high quality interfacial structure should be expected. Technologies to which this simple approach could be applied include but are not limited to p-n junctions of solar cells, battery electrode arrays, multiferroic materials, and plasmonic materials.

First claim

We claim:

1. A method for synthesizing a nanocomposite of aligned nanowires within a crystalline matrix comprising:
(a) depositing at least two metal nanodroplets on a surface of a metal oxide single crystalline matrix;
(b) etching negative nanowires into the surface of the crystalline matrix by solid-liquid-vapor etching with the metal nanodroplets; and
(c) filling the negative nanowires from (b) by vapor-liquid-solid growth with a metal oxide reactant vapor and the metal nanodroplets to form nanowires within the crystalline matrix, wherein the reactant vapor is a second material to the metal oxide of the crystalline matrix.

2. The method of claim 1 , further comprising removing the metal nanodroplets after step (c).

3. The method of claim 1 , wherein the crystalline matrix is selected from the group consisting of SnO 2 , ZnO, MgO, Ga 2 O 3 , TiO 2 , In 2 O 3 , Fe 2 O 3 , Fe 3 O 4 , CdO, γ-Al 2 O 3 , CaO, NiO, MnO, Eu 2 O 3 , and Sm 2 O 3 .

4. The method of claim 1 , wherein the metal nanodroplets comprise a metal selected from the group consisting of gold, gallium, silver, copper and platinum.

5. The method of claim 1 , wherein the reactant vapor is selected from the group consisting of SnO 2 , ZnO, MgO, Ga 2 O 3 , TiO 2 , In 2 O 3 , Fe 2 O 3 , Fe 3 O 4 , CdO, γ-Al 2 O 3 , CaO, NiO, MnO, Eu 2 O 3 , Sm 2 O 3 and elements contained therein.

6. The method of claim 1 , wherein the reactant vapor comprises a group IV or group 14 element, a III-V material or a II-VI material.

7. The method of claim 1 , wherein the etched negative nanowire is etched vertically with respect to the surface of the crystalline matrix.

8. The method of claim 1 , wherein the etched negative nanowire is etched horizontally along the surface of the crystalline matrix.

9. The method of claim 1 , wherein the etched negative nanowire is etched at an angle with respect to the surface of the crystalline matrix.

10. The method of claim 1 , further comprising continuing growth of the nanowire such that it protrudes above the surface of the crystalline matrix.

11. The method of claim 1 , wherein growth of the nanowire is discontinued such that the nanowire only partially fills the negative nanowire.

12. The method of claim 1 , wherein the metal nanodroplets are embedded into the crystalline matrix in (b) at the base of the etched negative nanowire.

13. The method of claim 1 , wherein the negative nanowire in (b) is etched to a depth to provide an adhesive force between the metal nanodroplet and walls of the negative nanowire.

14. The method of claim 1 , wherein the formed nanowires are contained within the crystalline matrix.

15. The method of claim 1 , wherein the formed nanowires extend beyond the surface of the crystalline matrix.

16. The method of claim 1 , wherein the nanodroplets reside at the tip of the formed nanowires.

Assignees

• Univ Kentucky Res Found

Inventors

• Guiton Beth S
• Yu Lei

Classifications

• H10P14/3402

  characterised by the chemical composition · CPC title

• H10P14/3426

  Oxides · CPC title

• H10P14/2926

  Crystal orientations · CPC title

• H10P14/2925

  Surface structures · CPC title

• H10P14/2921

  being crystalline insulating materials · CPC title