# US 2018/0025889 A1 · Nonthermal plasma synthesis

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- Number: US 2018/0025889 A1
- Document ID: US20180025889A1
- Status: Published application
- Kind: A1
- Application number: 15/648,843
- Filed: 2017-07-13
- Published: 2018-01-25
- Earliest claimed: 2016-07-22
- Applicants: Regents of the University of Minnesota
- Inventors: Katharine Hunter; Uwe Richard Kortshagen
- Web page: https://patentgrep.com/patent/US20180025889A1

## CPC

- H01J 37/32009: {Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources (plasma generation in general H05H1/24)}
- B22F 1/054: Nanosized particles
- B22F 1/16: Metallic particles coated with a non-metal (coated with lubricating or binding agents or with organic material B22F1/10)
- B22F 1/17: Metallic particles coated with metal
- B22F 1/18: Non-metallic particles coated with metal
- B22F 9/12: starting from gaseous material
- B22F 9/14: using electric discharge
- B82B 3/0019: {without movable or flexible elements}
- B82B 3/0033: {Manufacture or treatment of substrate-free structures, i.e. not connected to any support}
- B22F 2999/00: Aspects linked to processes or compositions used in powder metallurgy
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B82B: NANOSTRUCTURES FORMED BY MANIPULATION OF INDIVIDUAL ATOMS, MOLECULES, OR LIMITED COLLECTIONS OF ATOMS OR MOLECULES AS DISCRETE UNITS; MANUFACTURE OR TREATMENT THEREOF

## Abstract

An apparatus may include a nonthermal plasma reactor vessel, a gaseous core precursor inlet, a gaseous shell precursor inlet, and a plasma source. The reactor vessel may include a core formation region and a shell formation region downstream of the core formation region. The gaseous core precursor inlet may be upstream of the core formation region and configured to introduce gaseous core precursors to the reactor vessel. The gaseous shell precursor inlet may be downstream of the core formation region, upstream of the shell formation region, and configured to introduce gaseous shell precursors to the reactor vessel. The plasma source may be configured to produce a plasma in the core formation region and the shell formation region. The gaseous core precursors may form negatively-charged core nanoparticles in the core formation region. The gaseous shell precursors may form shells on the core nanoparticles in the shell formation region.

## Claims

### Claim 1

A method comprising:
powering, using a plasma source, a nonthermal plasma reactor to form a plasma in a core formation region and a shell formation region of the nonthermal plasma reactor, wherein the shell formation region is downstream of the core formation region;
introducing, upstream of the core formation region, gaseous core precursors, wherein the gaseous core precursors form negatively-charged core nanoparticles from the gaseous core precursors in the core formation region of the nonthermal plasma reactor; and
introducing, to the plasma downstream of the core formation region, gaseous shell precursors, wherein the gaseous shell precursors form shells on the core nanoparticles in the shell formation region of the nonthermal plasma reactor to produce core/shell nanoparticles.

### Claim 2 (depends on 1)

The method of claim 1, further comprising at least one of introducing a core inert gas with the gaseous core precursors or a shell inert gas with the gaseous shell precursors.

### Claim 3 (depends on 2)

The method of claim 2, wherein the at least one of the core inert gas or the shell inert gas comprises at least one of argon or helium.

### Claim 4 (depends on 2)

The method of claim 2, wherein the core inert gas and the shell inert gas are the same gas.

### Claim 5 (depends on 1)

The method of claim 1, wherein the plasma source comprises one or more electrodes and a power source.

### Claim 6 (depends on 5)

The method of claim 5, wherein the power source is a radiofrequency power source.

### Claim 7 (depends on 1)

The method of claim 1, further comprising introducing, to the nonthermal plasma reactor, gaseous dopant precursors.

### Claim 8 (depends on 7)

The method of claim 7, wherein the gaseous dopant precursors include at least one of boron or phosphorus.

### Claim 9 (depends on 1)

The method of claim 1, wherein the gaseous core precursors or gaseous shell precursors include at least one of group IV elements, metals, metal oxides, metal nitrides, or metal sulfides.

### Claim 10 (depends on 1)

The method of claim 1, further comprising collecting the core/shell nanoparticles downstream of the shell formation region.

### Claim 11 (depends on 10)

The method of claim 10, wherein collecting the core/shell nanoparticles comprises:
forming a beam of the core/shell nanoparticles; and
depositing the core/shell nanoparticles on a substrate to form a thin film.

### Claim 12 (depends on 11)

The method of claim 11, wherein the plasma includes a plasma density greater than 109 electrons·cm−3 at a location of the nonthermal plasma reactor at which the gaseous core precursors are introduced.

### Claim 13 (depends on 1)

The method of claim 1, wherein the core nanoparticles are core nanocrystals.

### Claim 14

An apparatus comprising:
a nonthermal plasma reactor vessel comprising;
a core formation region; and
a shell formation region downstream of the core formation region;
a gaseous core precursor inlet, upstream of the core formation region, configured to introduce gaseous core precursors to the reactor vessel;
a gaseous shell precursor inlet, downstream of the core formation region and upstream of the shell formation region, configured to introduce gaseous shell precursors to the reactor vessel;
a plasma source configured to produce a plasma in the core formation region and the shell formation region, wherein the gaseous core precursors form negatively-charged core nanoparticles from the gaseous core precursors in the core formation region of the reactor vessel, and where the gaseous shell precursors from shells on the core nanoparticles in the shell formation region of the reactor vessel.

### Claim 15 (depends on 14)

The apparatus of claim 14, wherein the gaseous core precursor inlet is further configured to introduce a core inert gas, or wherein the gaseous shell precursor inlet is further configured to introduce a shell inert gas, or both.

### Claim 16 (depends on 15)

The apparatus of claim 15, wherein at least one of the core inert gas or the shell inert gas comprises at least one of argon or helium.

### Claim 17 (depends on 15)

The apparatus of claim 15, wherein the core inert gas and the shell inert gas are the same gas.

### Claim 18 (depends on 14)

The apparatus of claim 14, wherein the plasma source comprises a power source electrically coupled to one or more electrodes.

### Claim 19 (depends on 18)

The apparatus of claim 18, wherein the power source is a radiofrequency power source.

### Claim 20 (depends on 14)

The apparatus of claim 14, wherein the gaseous core precursor inlet or the gaseous shell precursor inlet is further configured to introduce gaseous dopant precursors to the reactor vessel.

### Claim 21 (depends on 20)

The apparatus of claim 20, wherein the gaseous dopant precursors include at least one of boron or phosphorus.

### Claim 22 (depends on 14)

The apparatus of claim 14, wherein the gaseous core precursors or gaseous shell precursors include at least one of group IV elements, metals, metal oxides, metal nitrides, or metal sulfides.

### Claim 23 (depends on 14)

The apparatus of claim 14, further comprising a nanoparticle collection unit downstream of the shell formation region.

### Claim 24 (depends on 23)

The apparatus of claim 23, wherein the nanoparticle collection unit comprises a nanoparticle orifice and a substrate, wherein the nanoparticle orifice is configured to form a nanoparticle beam that deposits a thin film on the substrate.

### Claim 25 (depends on 14)

The apparatus of claim 14, wherein the plasma includes a plasma density greater than 109 electrons·cm−3 at the gaseous core precursor inlet.

### Claim 26 (depends on 14)

The apparatus of claim 14, wherein the core nanoparticles are core nanocrystals.

### Claim 27

A system comprising:
a controller configured to:
control a plasma source to power a nonthermal plasma reactor to form a plasma in a core formation region and a shell formation region of the nonthermal plasma reactor, wherein the shell formation region is downstream of the core formation region;
control a gaseous core precursor inlet, upstream of the core formation region, to introduce gaseous core precursors to the nonthermal plasma reactor, wherein the gaseous core precursors form negatively-charged core nanoparticles from the gaseous core precursors in the core formation region of the nonthermal plasma reactor; and
control a gaseous shell precursor inlet, downstream of the core formation region and upstream of the shell formation region, to introduce gaseous shell precursors to the nonthermal plasma reactor, wherein the gaseous shell precursors form shells on the core nanoparticles in the shell formation region of the nonthermal plasma reactor.

### Claim 28

A computer-readable storage medium storing instructions that, when executed, cause a processor to:
power, using a plasma source, a nonthermal plasma reactor to form a plasma in a core formation region and a shell formation region of the nonthermal plasma reactor, wherein the shell formation region is downstream of the core formation region;
introduce, upstream of the core formation region, gaseous core precursors, wherein the gaseous core precursors form negatively-charged core nanoparticles from the gaseous core precursors in the core formation region of the nonthermal plasma reactor; and
introduce, to the plasma downstream of the core formation region, gaseous shell precursors, wherein the gaseous shell precursors form shells on the core nanoparticles in the shell formation region of the nonthermal plasma reactor.