# US 2018/0323387 A1 · Unipolar N- or P-Type Carbon Nanotube Transistors and Methods of Manufacture Thereof

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- Number: US 2018/0323387 A1
- Document ID: US20180323387A1
- Status: Published application
- Kind: A1
- Application number: 15/971,987
- Filed: 2018-05-04
- Published: 2018-11-08
- Earliest claimed: 2017-05-04
- Applicants: Atom Nanoelectronics, Inc.
- Inventors: Huaping Li
- Web page: https://patentgrep.com/patent/US20180323387A1

## CPC

- H10K 10/468: {characterised by the gate dielectrics}
- H10K 10/484: {characterised by the channel regions}
- H10K 10/84: Ohmic electrodes, e.g. source or drain electrodes
- H10K 71/30: Doping active layers, e.g. electron transporting layers
- H10K 85/221: {Carbon nanotubes}
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites
- B82Y 40/00: Manufacture or treatment of nanostructures
- H10K 10/464: {Lateral top-gate IGFETs comprising only a single gate}
- H10K 10/466: {Lateral bottom-gate IGFETs comprising only a single gate}
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

Devices, materials and methods for producing and integrating carbon nanotubes (CNT) into TFTs to form unipolar CNT TFTs are provided. CNT TFTs comprise doped layers between the CNT active layer and the source/drain electrodes capable of providing a carrier-trapping function such that unwanted carrier charge injection is suppressed between the electrodes allowing for the unipolar operation of CNT TFTs. Methods and apparatus for forming unipolar N- or P-type SWCNT TFTs are also provided.

## Claims

### Claim 1

A unipolar thin film transistor comprising
at least a first dielectric layer;
at least one carbon nanotube active layer, at least a portion of which is in contact with the at least first dielectric layer;
at least one gate electrode such that the at least first dielectric layer is interposed between the one carbon nanotube active layer and the at least one gate electrode;
at least a drain and a source electrode disposed over or under the at least one carbon nanotube active layer
at least one n+ or p+ doped layer disposed between the at least one carbon nanotube active layer and the drain and source electrodes, such that the TFT demonstrates unipolar characteristics.

### Claim 2 (depends on 1)

The unipolar thin film transistor of claim 1, wherein the doped layer is n+ doped such that the doped layer eliminates a P-type charge carrier injection and transportation in the TFT such that the TFT exhibits an N-type property.

### Claim 3 (depends on 1)

The unipolar thin film transistor of claim 1, wherein the doped layer is p+ doped such that the doped layer eliminates an N-type charge carrier injection and transportation in the TFT such that the TFT exhibits a P-type property.

### Claim 4 (depends on 1)

The unipolar thin film transistor of claim 1, wherein the doped layer is formed from one of a amorphous, microcrystalline or polycrystalline material selected from the group of: silicon, arsenides and phosphides of gallium, and tellurides and sulfides of cadmium;
and wherein the material is doped with a substance selected from the group of phosphorous, arsenic, antimony, bismuth, lithium, beryllium, zinc, chromium, germanium, magnesium, tin, lithium, and sodium, phosphine and diborane.

### Claim 5 (depends on 1)

The unipolar thin film transistor of claim 1, wherein the at least first dielectric layer is formed of a material selected from the group consisting of inorganic and organic materials, an oxide, a nitride, and a nitrogen oxide.

### Claim 6 (depends on 5)

The unipolar thin film transistor of claim 5, wherein the at least first dielectric layer is selected from the group of HfOx, SiNx, SiOx, TaOx, AlOx, Y2O3, and Si(ON)x.

### Claim 7 (depends on 1)

The unipolar thin film transistor of claim 1, wherein the drain and source electrodes are single or multilayer structures formed of one or more of the following materials Cu, Al, Ag, Mo, Cr, Nd, Ni, Mn, Ti, Ta or W.

### Claim 8 (depends on 1)

The unipolar thin film transistor of claim 1, wherein the carbon nanotube active layers if formed from one of either double walled carbon nanotubes or single-walled carbon nanotubes.

### Claim 9 (depends on 8)

The unipolar thin film transistor of claim 8, wherein the single-walled carbon nanotubes are high purity single chirality single-walled carbon nanotubes having an index selected from (6,4), (9,1), (8,3), (6,5), (7,3), (7,5), (10,2), (8,4), (7,6), (9,2), and mixtures thereof.

### Claim 10 (depends on 1)

The unipolar thin film transistor of claim 1, wherein the at least one gate is configured as a top-gate.

### Claim 11 (depends on 1)

The unipolar thin film transistor of claim 1, the at least one gate is configured as a bottom-gate.

### Claim 12 (depends on 1)

The unipolar thin film transistor of claim 1, further comprising a substrate in supportive relationship with the remaining elements of the unipolar thin film transistor.

### Claim 13 (depends on 1)

The unipolar thin film transistor of claim 1, wherein the on to off ratio of the transistor is greater than 1E7.

### Claim 14 (depends on 1)

The unipolar thin film transistor of claim 1, wherein the transistor mobility is greater than 10 cm2/Vs.

### Claim 15 (depends on 1)

The unipolar thin film transistor of claim 1, wherein the active layer may comprise one of a network of carbon nanotubes or aligned and organized sheets of carbon nanotubes.

### Claim 16 (depends on 1)

The unipolar thin film transistor of claim 1, wherein the doped layer is formed of an ion implanted carbon nanotube material.

### Claim 17

A method for manufacturing a unipolar thin film transistor comprising one of either a bottom-gate or a top-gate process:
wherein the bottom-gate process comprises:
providing a substrate,
patterning a gate electrode and dielectric layer on the substrate,
depositing an active-layer comprised of a thin-film layer of single-walled carbon nanotubes on said dielectric layer,
patterning at least a doped layer, and a drain and a source electrode either below or above the active-layer such that the portion of the active-layer overlapping the channel is exposed, and such that the doped layer is disposed between the drain and the source electrode and the active-layer, and
wherein the doped layer is one of either n+ or p+ doped, such that the TFT demonstrates unipolar characteristics; and
wherein the top-gate process comprises:
providing a substrate;
depositing a dielectric layer on the substrate;
depositing an active-layer comprised of a thin-film layer of single-walled carbon nanotubes on the dielectric layer;
patterning a gate electrode and dielectric layer on the active layer to form a channel;
patterning at least a doped layer, and a drain and a source electrode either below or above the active-layer using a photomask and photolithography process such that the portion of the dielectric overlapping the channel is exposed; and
wherein the doped layer is one of either n+ or p+ doped, such that the TFT demonstrates unipolar characteristics.

### Claim 18 (depends on 17)

The method of one of either claims 17, wherein the active-layer is deposited by a technique selected from the group consisting of solution coating, spraying, aerosol jet printing, or transferring.

### Claim 19 (depends on 17)

The method of one of either claims 17, wherein the thin-film active layer comprises one of either a network of carbon nanotubes or aligned and organized sheets of carbon nanotubes.

### Claim 20 (depends on 17)

The method of one of either claims 17, wherein the doped layer comprises one of either the material of the active layer treated with ion implantation, or a separate doped material.

### Claim 21 (depends on 20)

The method of claim 20, wherein the doped layer is formed from a separate doped material, and wherein the doped material is deposited using a technique selected from the group of aerosol assisted CVD, direct liquid injection CVD, microwave plasma-assisted CVD, atomic layer CVD, combustion chemical vapor deposition, hot filament CVD, hybrid physical-chemical vapor deposition, rapid thermal CVD, vapor-phase epitaxy, photo-initiated CVD, and atomic layer deposition.

### Claim 22 (depends on 17)

The method of one of either claims 17, wherein the doped layer is n+ doped such that the doped layer eliminates a P-type charge carrier injection and transportation in the TFT such that the TFT exhibits an N-type property.

### Claim 23 (depends on 17)

The method of one of either claims 17, wherein the doped layer is p+ doped such that the doped layer eliminates an N-type charge carrier injection and transportation in the TFT such that the TFT exhibits a P-type property.

### Claim 24 (depends on 17)

The method of one of either claims 17, wherein the doped layer is formed from one of an amorphous, microcrystalline or polycrystalline material selected from the group of: silicon, arsenides and phosphides of gallium, and tellurides and sulfides of cadmium; and wherein the material is doped with a substance selected from the group of phosphorous, arsenic, antimony, bismuth, lithium, beryllium, zinc, chromium, germanium, magnesium, tin, lithium, and sodium, phosphine and diborane.

### Claim 25 (depends on 17)

The method of one of either claims 17, wherein the dielectric layer is formed of a material selected from the group consisting of inorganic and organic materials, an oxide, a nitride, and a nitrogen oxide.

### Claim 26 (depends on 25)

The method of claim 25, wherein the dielectric layer is selected from the group of HfOx, SiNx, SiOx, TaOx, AlOx, Y2Ox, and Si(ON)x.

### Claim 27 (depends on 17)

The method of one of either claims 17, wherein the drain and source electrode layers are single or multilayer structures formed of one or more of the following materials Cu, Al, Ag, Mo, Cr, Nd, Ni, Mn, Ti, Ta or W.

### Claim 28 (depends on 17)

The method of one of either claims 17, wherein the carbon nanotubes are one of either double walled carbon nanotubes or single-walled carbon nanotubes.

### Claim 29 (depends on 28)

The method of claim 28, wherein the single-walled carbon nanotubes are high purity single chirality single-walled carbon nanotubes having an index selected from (6,4), (9,1), (8,3), (6,5), (7,3), (7,5), (10,2), (8,4), (7,6), (9,2), and mixtures thereof.