# US 8,772,141 B2 · Doping carbon nanotubes and graphene for improving electronic mobility

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- Number: US 8,772,141 B2
- Document ID: US8772141B2
- Status: Granted
- Kind: B2
- Application number: 13/627,020
- Filed: 2012-09-26
- Published: 2013-05-30
- Granted: 2014-07-08
- Earliest claimed: 2011-11-29
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Ali Afzali-Ardakani; Bhupesh Chandra; George Stojan Tulevski
- Web page: https://patentgrep.com/patent/US8772141B2

## CPC

- H10D 30/47: having two-dimensional [2D] charge carrier gas channels, e.g. nanoribbon FETs or high electron mobility transistors [HEMT]
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- H10D 30/481: {FETs having two-dimensional material channels, e.g. transition metal dichalcogenide [TMD] FETs}
- H10D 62/882: {Graphene}
- H10K 71/30: Doping active layers, e.g. electron transporting layers
- H10K 85/221: {Carbon nanotubes}
- H10K 10/484: {characterised by the channel regions}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES

## Abstract

A method for doping a graphene or nanotube thin-film field-effect transistor device to improve electronic mobility. The method includes selectively applying a dopant to a channel region of a graphene or nanotube thin-film field-effect transistor device to improve electronic mobility of the field-effect transistor device.

## Claims

### Claim 1

A method for doping a graphene field-effect transistor device to improve electronic mobility, comprising:
selectively applying a dopant to a channel region of a graphene field-effect transistor device to improve electronic mobility of the field-effect transistor device, wherein said dopant comprises at least one of cerium ammonium nitrate and cerium ammonium sulfate.

### Claim 2 (depends on 1)

The method of claim 1, further comprising depositing contact metal over the doped channel region of the graphene field-effect transistor device.

### Claim 3 (depends on 1)

The method of claim 1, wherein the dopant is a dopant solution.

### Claim 4 (depends on 3)

The method of claim 3, wherein the dopant solution comprises a mixture of at least one charge transfer doping compound in a solvent at a concentration in a range of 0.1 millimole (mM) to 100 mM.

### Claim 5 (depends on 4)

The method of claim 4, wherein the at least one charge transfer doping compound comprises ruthenium bipyridyl complex.

### Claim 6 (depends on 4)

The method of claim 4, wherein the at least one charge transfer doping compound comprises triethyloxonium hexachloro antimonate.

### Claim 7 (depends on 4)

The method of claim 4, wherein the solvent comprises at least one of water, dichloroethane, alcohol, and dichlorobenzene.

### Claim 8 (depends on 1)

The method of claim 1, wherein the dopant is in a gel mixture in which the gel evaporates after application.

### Claim 9 (depends on 1)

The method of claim 1, wherein selectively applying a dopant to a channel region of a graphene field-effect transistor device comprises placing the graphene field-effect transistor device in a dopant solution for a duration of time.

### Claim 10 (depends on 9)

The method of claim 9, wherein the duration of time comprises a range of one second to ten hours.

### Claim 11 (depends on 9)

The method of claim 9, wherein the duration of time is based on a concentration of the dopant being applied.

### Claim 12 (depends on 9)

The method of claim 9, further comprising removing the graphene field-effect transistor device from the dopant solution and via rinsing with a dopant solvent.

### Claim 13 (depends on 1)

The method of claim 1, wherein selectively applying a dopant to a channel region of a graphene field-effect transistor device to improve electronic mobility of the field-effect transistor device further comprises decreasing resistance of the field-effect transistor device.

### Claim 14 (depends on 1)

The method of claim 1, wherein selectively applying a dopant to a channel region of a graphene field-effect transistor device comprises stamping the dopant directly over a channel area of the graphene field-effect transistor device.

### Claim 15 (depends on 14)

The method of claim 14, wherein stamping comprises using one of a polymer based stamp, ink jet printing, brushing, and screen printing.

### Claim 16

A method for doping a carbon nanotube thin-film transistor (CNT-TFT) device to improve electronic mobility, comprising:
selectively applying a dopant to a channel region of a carbon nanotube thin-film transistor (CNT-TFT) device to improve electronic mobility of the transistor device, wherein said dopant comprises at least one of cerium ammonium nitrate and cerium ammonium sulfate.

### Claim 17 (depends on 16)

The method of claim 16, further comprising depositing contact metal over the doped channel region of the nanotube thin-film transistor (CNT-TFT) device.

### Claim 18 (depends on 16)

The method of claim 16, wherein the dopant comprises a dopant solution comprising a mixture of at least one charge transfer doping compound in a solvent at a concentration in a range of 0.1 millimole (mM) to 100 mM, wherein the at least one charge transfer doping compound comprises at least one of ruthenium bipyridyl complex, and triethyloxonium hexachloro antimonite.