# US 10,768,109 B2 · Chemical sensing based on plasmon resonance in carbon nanotubes

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- Number: US 10,768,109 B2
- Document ID: US10768109B2
- Status: Granted
- Kind: B2
- Application number: 16/238,890
- Filed: 2019-01-03
- Published: 2019-05-09
- Granted: 2020-09-08
- Earliest claimed: 2017-01-03
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Ali Afzali-Ardakani; Abram L. Falk; Damon B. Farmer; Shu-Jen Han; George S. Tulevski
- Web page: https://patentgrep.com/patent/US10768109B2

## CPC

- G01N 21/554: {detecting the surface plasmon resonance of nanostructured metals, e.g. localised surface plasmon resonance}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

A method of forming a chemical sensor includes forming a dielectric layer on an electrode. A carbon nanotube film is deposited on the dielectric layer. The carbon nanotube film is patterned into strips.

## Claims

### Claim 1

A method of forming a chemical sensor, comprising:
forming a dielectric layer on an electrode, including an oxide layer and a non-polar spacer layer;
depositing a carbon nanotube film on the non-polar spacer layer of the dielectric layer, wherein the non-polar spacer layer controls coupling between polar photons in the oxide layer and plasmons in the carbon nanotube film;
patterning the carbon nanotube film into a plurality of strips having a plasmon mode that overlaps with a vibrational mode of a chemical to be detected; and
forming conductive contacts at ends of each of the plurality of strips.

### Claim 2 (depends on 1)

The method of claim 1, wherein depositing the carbon nanotube film on the dielectric layer comprises depositing the carbon nanotube using a Langmuir-Schafer process.

### Claim 3 (depends on 2)

The method of claim 2, wherein depositing the carbon nanotube film comprises forming a film of nanotubes having a thickness between about 2 nm and about 10 nm.

### Claim 4 (depends on 3)

The method of claim 3, wherein depositing the carbon nanotube film comprises forming a film of nanotubes having a thickness of about 6 nm.

### Claim 5 (depends on 2)

The method of claim 2, wherein depositing the carbon nanotube film comprises forming a film of nanotubes of about 99.9% pure semiconducting nanotubes.

### Claim 6 (depends on 1)

The method of claim 1, wherein patterning the carbon nanotube film comprises forming a mask on the carbon nanotube film and etching portions of the carbon nanotube film that are not covered by the mask.

### Claim 7 (depends on 6)

The method of claim 6, wherein etching comprises an oxygen reactive ion etch process.

### Claim 8 (depends on 1)

The method of claim 1, further comprising connecting the conductive contacts to a signal analyzer configured to detect currents generated by the respective strips.

### Claim 9 (depends on 1)

The method of claim 1, wherein patterning the carbon nanotube film comprises forming gaps between the plurality of strips of carbon nanotubes, the gaps having a width between 50 nm and 500 nm.

### Claim 10 (depends on 9)

The method of claim 9, wherein patterning the carbon nanotube film forms the plurality of strips with about the same width as the gaps.

### Claim 11

A method of forming a chemical sensor, comprising:
forming a dielectric layer on an electrode, including a silicon dioxide layer and a diamond-like carbon non-polar spacer layer on the silicon dioxide layer, the diamond-like carbon layer having a thickness of less than 40 nm;
forming a doped carbon nanotube film on the non-polar spacer layer of the dielectric layer using a Langmuir-Schafer process, wherein the non-polar spacer layer controls coupling between polar photons in the oxide layer and plasmons in the carbon nanotube film;
patterning the carbon nanotube film into a plurality of strips having a plasmon mode that overlaps with a vibrational mode of a chemical to be detected; and
forming conductive contacts at ends of each of the plurality of strips.

### Claim 12 (depends on 11)

The method of claim 11, wherein depositing the carbon nanotube film comprises forming a film of nanotubes having a thickness between about 2 nm and about 10 nm.

### Claim 13 (depends on 12)

The method of claim 12, wherein depositing the carbon nanotube film comprises forming a film of nanotubes having a thickness of about 6 nm.

### Claim 14 (depends on 11)

The method of claim 11, wherein depositing the carbon nanotube film comprises forming a film of nanotubes of about 99.9% pure semiconducting nanotubes.

### Claim 15 (depends on 11)

The method of claim 11, wherein patterning the carbon nanotube film comprises forming a mask on the carbon nanotube film and etching portions of the carbon nanotube film that are not covered by the mask.

### Claim 16 (depends on 15)

The method of claim 15, wherein etching comprises an oxygen reactive ion etch process.

### Claim 17 (depends on 11)

The method of claim 11, further comprising connecting the conductive contacts to a signal analyzer configured to detect currents generated by the respective strips.

### Claim 18 (depends on 11)

The method of claim 11, wherein patterning the carbon nanotube film comprises forming gaps between the plurality of strips of carbon nanotubes, the gaps having a width between 50 nm and 500 nm.

### Claim 19 (depends on 18)

The method of claim 18, wherein patterning the carbon nanotube film forms the plurality of strips with about the same width as the gaps.

### Claim 20 (depends on 11)

The method of claim 11, wherein forming the doped carbon nanotube film comprises exposing a nanotube film to NO2 gas.