Molecular tunnel junctions and their use as sources of electronic plasmons

Patent metadata

Field	Value
Publication number	US-10094957-B2
Application number	US-201715470030-A
Country	US
Kind code	B2
Filing date	Mar 27, 2017
Priority date	Mar 30, 2016
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

A method of producing electronic plasmons by applying a bias to a molecular tunnel junction to excite plasmons, in which the molecular tunnel junction contains a top metallic electrode formed of a eutectic metal alloy and a metal oxide, a bottom metallic electrode formed of a transition metal, and a self-assembled monolayer formed of a plurality of organic molecules disposed between the top metallic electrode and the bottom metallic electrode. Also disclosed are a molecular tunnel junction for producing electronic plasmons and a method for preparing such a molecular tunnel junction.

First claim

What is claimed is:

1. A method of producing electronic plasmons, the method comprising:
providing a molecular tunnel junction,
applying a bias to the molecular tunnel junction to excite plasmons, and
detecting the plasmons thus produced,

wherein the molecular tunnel junction contains a top metallic electrode formed of a eutectic metal alloy and a metal oxide, a bottom metallic electrode formed of a transition metal, and a self-assembled monolayer formed of a plurality of organic molecules disposed between the top metallic electrode and the bottom metallic electrode.

2. The method of claim 1 , wherein the plurality of organic molecules each contain a —SR thiolate moiety, in which R is a molecular chain formed of an alkyl group, an alkynyl group, an aryl group, a heteroaryl group, a metallocene group, a redox-active group, an optically active group, or a combination thereof.

3. The method of claim 2 , wherein the SR thiolate moiety contains an alkyl chain.

4. The method of claim 3 , wherein the —SR thiolate moiety is —S(CH 2 ) n-1 CH 3 , n being 10, 12, 14, 16, or 18.

5. The method of claim 2 , wherein the plurality of organic molecules are a plurality of molecular diodes each formed of a —SR thiolate moiety, in which R is a molecular chain containing an aryl group, a heteroaryl group, or a metallocene group; and the plurality of molecular diodes enable bias selective plasmon excitation.

6. The method of claim 5 , wherein the —SR thiolate moiety is

7. The method of claim 1 , wherein the molecular tunnel junction contains a self-assembled monolayer formed of a plurality of molecular diodes that enable either direct plasmon excitation or directional plasmon excitation.

8. The method of claim 1 , wherein the plasmon excitation is enabled via direct quantum mechanical tunneling.

9. The method of claim 1 , wherein the plasmon excitation has a metal-insulator-metal surface plasmon polariton (SPP) mode, a surface propagating plasmon mode, or a localized surface plasmon mode.

10. The method of claim 1 , wherein the plurality of organic molecules enable direct propagating SPP excitation by using a gold strip bottom electrode.

11. The method of claim 1 , wherein the plurality of organic molecules enable direct plasmon excitation or directional plasmon excitation by using a gold waveguide bottom electrode.

12. The method of claim 1 , wherein the plurality of organic molecules enable bias selective plasmon excitation via direct quantum mechanical tunneling.

13. The method of claim 12 , wherein the bias selective plasmon excitation has a metal-insulator-metal SPP mode, a surface propagating plasmon mode, or a localized surface plasmon mode.

14. The method of claim 1 , wherein the top metallic electrode is formed of a eutectic metal alloy and a metal oxide, in which the eutectic metal alloy is EGaIn and the metal oxide is Ga 2 O 3 .

15. The method of claim 1 , wherein the bottom metallic electrode is formed of a transition metal selected from the group consisting of Au, Ag, Cu, Ni, Pt, and Pd.

16. The method of claim 1 , wherein the plurality of organic molecules each contain a —SR thiolate moiety, the —SR thiolate moiety being covalently bond to the bottom metallic electrode through a metal-thiolate bond and being non-covalently bond to the top metallic electrode through van der Waals interactions.

17. The method of claim 1 , wherein the plasmon excitation is enabled via directional tunneling that is modulated by the tilt angle of the self-assembled monolayer with respect to the bottom metallic electrode.

18. The method of claim 17 , wherein the tilt angle is modulated by interactions between the plurality of organic molecules and the bottom metallic electrode.

19. The method of claim 17 , wherein the self-assembled monolayer has a tilt angle of 10°-30°, inclusive, with respect to the bottom metallic electrode.

20. A molecular tunnel junction for producing electronic plasmons, comprising:
a top metallic electrode formed of an eutectic metal alloy and a metal oxide,
a bottom metallic electrode formed of a template-striped metal, and
a self-assembled monolayer formed of a plurality of molecular diodes disposed between the top metallic electrode and the bottom metallic electrode,

wherein the plurality of molecular diodes each contain a —SR thiolate moiety, in which R is a molecular chain containing an aryl group, a heteroaryl group, or a metallocene group, and an alkynyl group; and the plurality of molecular diodes enable bias selective plasmon excitation.

21. The molecular tunnel junction of claim 20 , further comprising an optical adhesive layer and a substrate layer, the substrate layer attached to the bottom metallic electrode via the optical adhesive layer.

22. The molecular tunnel junction of claim 20 , wherein the top metallic electrode is formed of a eutectic metal alloy and a metal oxide, in which the eutectic metal alloy is EGaIn and the metal oxide is Ga 2 O 3 .

23. The molecular tunnel junction of claim 20 , wherein the bottom metallic electrode is formed of a transition metal selected from the group consisting of Au, Ag, Cu, Ni, Pt, and Pd.

24. The molecular tunnel junction of claim 20 , wherein the plurality of molecular diodes each contain a —SR thiolate moiety, the —SR thiolate moiety being covalently bond to the bottom metallic electrode through a metal-thiolate bond and being non-covalently bond to the top metallic electrode through van der Waals interactions.

25. The molecular tunnel junction of claim 24 , wherein the —SR thiolate moiety is

26. The molecular tunnel junction of claim 25 , wherein the self-assembled monolayer has a tilt angle of 10°-30°, inclusive, with respect to the bottom metallic electrode.

27. A method of fabricating a molecular tunnel junction of claim 20 , the method comprising:
providing a bottom metallic electrode formed of a template-striped metal,
depositing onto the bottom metallic electrode a plurality of molecular diodes to form a self-assembled monolayer, and
forming a top metallic electrode onto the self-assembled monolayer,
wherein the plurality of molecular diodes each contain a —SR thiolate moiety, in which R is a molecular chain containing an aryl group, a heteroaryl group, or a metallocene group, and an alkynyl group; and the plurality of molecular diodes enable bias selective plasmon excitation without the need of an optical element.

Assignees

• Nat Univ Singapore
• Agency Science Tech & Res

Inventors

• Du Wei
• Wang Tao
• Nijhuis Christian Albert
• Chu Hong-Son
• Wu Lin

Classifications

• Y10S977/892

  Liquid phase deposition · CPC title

• B82Y20/00

  Nanooptics, e.g. quantum optics or photonic crystals · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• Y10S977/81

  Of specified metal or metal alloy composition · CPC title

• Y10S977/811

  Of specified metal oxide composition, e.g. conducting or semiconducting compositions such as ITO, ZnOx · CPC title