Heteroepitaxial structure and method for forming the same, and nanogap electrode

Patent metadata

Field	Value
Publication number	US-2021213707-A1
Application number	US-202117213527-A
Country	US
Kind code	A1
Filing date	Mar 26, 2021
Priority date	Oct 2, 2018
Publication date	Jul 15, 2021
Grant date	—

Abstract

A heteroepitaxial structure includes a first metal portion having a polycrystalline structure, a second metal portion on the first metal portion, the second metal portion has an island-shaped structure on the first metal portion, the second metal portion is provided corresponding to at least one crystalline grain exposed to a surface of the first metal portion, and the second metal portion and the at least one crystalline grain have a heteroepitaxial interface.

First claim

What is claimed is:

1 . A heteroepitaxial structure, comprising:
a first metal portion having a polycrystalline structure; a second metal portion on the first metal portion; the second metal portion has an island-shaped structure on the first metal portion; the second metal portion is provided corresponding to at least one crystalline grain exposed to a surface of the first metal portion; and the second metal portion and the at least one crystalline grain have a heteroepitaxial interface.

2 . The heteroepitaxial structure according to claim 1 , wherein the first metal portion comprises a metal element selected from platinum (Pt), palladium (Pd), rhodium (Rd), ruthenium (Ru), osmium (Os) and iridium (Ir), and the second metal portion is gold (Au).

3 . The heteroepitaxial structure according to claim 1 , wherein the first metal portion is palladium (Pd), the second metal portion is gold (Au), and the interface between the first metal portion and the second metal portion includes a solid solution of the first metal portion and the second metal portion.

4 . The heteroepitaxial structure according to claim 1 , wherein the island-shaped structure is a mountain shape or a hemispherical shape.

5 . A method for forming heteroepitaxial structure, the method comprising:
dipping a first metal portion having a polycrystalline structure in an electroless plating solution containing a metal ion of a second metal different from the first metal portion, an ion of a halogen element as an oxidizing agent, and a reducing agent; and heteroepitaxial growing a metal reduced from a metal ion of the second metal by a surface limited redox replacement corresponding to a reduced surface of at least one crystalline grain of the first metal portion while reducing the surface of the first metal portion by the oxidizing agent and the reducing agent.

6 . The method for forming heteroepitaxial structure according to claim 5 , wherein forming a heteroepitaxial interface with the at least one crystalline grain by heteroepitaxial growth, and forming a second metal portion having an island-shaped structure on a surface of the first metal portion.

7 . The method for forming heteroepitaxial structure according to claim 5 , wherein the first metal portion is platinum, the metal ion is gold ion (Au + , Au 3+ ), the ion of the halogen element is iodine ion (I − , I 3 − ), and the reducing agent is L(+)-ascorbic acid (C 6 H 8 O 8 ).

8 . The method for forming heteroepitaxial structure according to claim 5 , wherein the electroless plating solution is diluted 500 times or more with water.

9 . The method for forming heteroepitaxial structure according to claim 7 , wherein dipping the first metal portion in iodine tincture and L(+)-ascorbic acid (C 6 H 8 O 6 ) before dipping in the electroless plating solution.

10 . A nanogap electrode, comprising:
a first electrode and a second electrode each including a first metal portion and a second metal portion on the first metal portion, the first metal portion having a polycrystalline structure, wherein the first metal portion has a linear pattern having a width of 20 nm or less, the second metal portion is disposed at least on one end of the linear pattern of the first metal portion and has an island-shaped structure, a heteroepitaxial interface is formed corresponding to at least one crystalline grain exposed to a surface of the first metal portion, and a distance between the second metal portions on the first electrode and on the second electrode is 5 nm or less.

11 . The nanogap electrode according to claim 10 , wherein the second metal portion includes a plurality of crystal regions having different crystal orientations.

12 . The nanogap electrode according to claim 10 , wherein the second metal portion has a hemispherical shape.

13 . The nanogap electrode according to claim 10 , wherein the first metal portion comprises a metal element selected from platinum (Pt), palladium (Pd), rhodium (Rd), ruthenium (Ru), osmium (Os) and iridium (Ir), and the second metal portion is gold (Au).

14 . The nanogap electrode according to claim 10 , wherein the first metal portion is palladium (Pd), the second metal portion is gold (Au), and an interface between the first metal portion and the second metal portion includes a solid solution of the first metal portion and the second metal portion.

15 . The nanogap electrode according to claim 10 , wherein the second metal portion is disposed at one end on a substantially central axis of the linear pattern of the first metal portion.

16 . The nanogap electrode according to claim 10 , wherein the first metal portion has a linear pattern having a width of 15 nm or less.

Assignees

• Japan Science & Tech Agency

Inventors

• Majima Yutaka
• Choi Yoonyoung
• Shimada Ikuko
• Toyama Ryo
• Yang Mingyue

Classifications

• C23C18/1637

  metallic substrate · CPC title

• C23C30/00

  Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process (C23C26/00, C23C28/00 take precedence) · CPC title

• C23C28/02

  only coatings {only including layers} of metallic material · CPC title

• C23C18/44

  using reducing agents · CPC title

• C23C18/1651

  Two or more layers only obtained by electroless plating · CPC title