# US 8,540,892 B1 · Ion etching of growing InP nanocrystals using microwave

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- Number: US 8,540,892 B1
- Document ID: US8540892B1
- Status: Granted
- Kind: B1
- Application number: 13/645,898
- Filed: 2012-10-05
- Granted: 2013-09-24
- Earliest claimed: 2008-07-10
- Assignees: The Florida State University Research Foundation, Inc.
- Applicants: The Florida State University Research Foundation, Inc.
- Inventors: Geoffrey F. Strouse; Derek D. Lovingood
- Web page: https://patentgrep.com/patent/US8540892B1

## CPC

- C30B 29/605: {Products containing multiple oriented crystallites, e.g. columnar crystallites}
- C30B 7/14: the crystallising materials being formed by chemical reactions in the solution
- C30B 29/40: AIIIBV compounds {wherein A is B, Al, Ga, In or Tl and B is N, P, As, Sb or Bi}
- C30B 30/02: using electric fields, e.g. electrolysis
- B82Y 40/00: Manufacture or treatment of nanostructures
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

High quantum yield InP nanocrystals are used in the bio-technology, bio-medical, and photovoltaic, specifically IV, III-V and III-VI nanocrystal technological applications. InP nanocrystals typically require post-generation HF treatment. Combining microwave methodologies with the presence of a fluorinated ionic liquid allows Fluorine ion etching without the hazards accompanying HF. Growing the InP nanocrystals in the presence of the ionic liquid allows in-situ etching to be achieved. The optimization of the PL QY is achieved by balancing growth and etching rates in the reaction.

## Claims

### Claim 1

A method of producing nanoparticles exhibiting enhanced photoluminescence quantum yield comprising the steps of:
providing stock solutions of Group III-VI elements;
providing an ionic liquid containing an anion that thermally degrades to form an ion etchant, wherein the anion is BF4, PF6, F, ClO4, PO4, chloride, bromide, acetate, or hydroxide;
placing the ionic liquid into a microwave reactor vessel;
dissolving the stock solutions of Group III-VI elements in a solute and injecting the resulting solution into the microwave reactor vessel;
subjecting the microwave reactor vessel to an inert atmosphere, wherein the inert atmosphere contacts the stock solutions of Group III-VI elements and the ionic liquid;
subjecting the solutions in the microwave reactor vessel to microwave irradiation, wherein the microwave irradiation degrades the anion of the ionic liquid into an etchant;
where the etchant is F−, Cl−, Br−, or O−;
allowing the stock solutions of Group III-VI elements to form nanoparticles, wherein the nanoparticles are etched in situ by the etchant during nanoparticle growth; and
collecting the resulting nanoparticles.

### Claim 2 (depends on 1)

The method of claim 1, wherein the microwave irradiation is ramped at 300 W.

### Claim 3 (depends on 1)

The method of claim 1, further comprising ramping the reaction between 1 minute and 25 minutes.

### Claim 4 (depends on 1)

The method of claim 1, wherein the ionic liquid comprises 1-hexyl-3-methyl-imidazolium, 1-butyl-4-methyl-pyridinium, tetrabutylammonium, or their derivatives.

### Claim 5 (depends on 4)

The method of claim 4, wherein the ionic liquid is used at a molar concentration ratio between 1:1 and 1:10, stock solutions of Group III-VI elements to ionic liquid.

### Claim 6 (depends on 1)

The method of claim 1, wherein the resulting nanoparticles are collected by using at least one compound selected from the group consisting of toluene, acetone, and methanol.

### Claim 7 (depends on 1)

The method of claim 1, further comprising the step of cooling the reaction site after formation of the nanoparticles using forced air cooling.

### Claim 8 (depends on 1)

The method of claim 1, wherein stock solutions of Group III-VI elements are indium, indium palmitate, tris-trimethylsilylphosphine, gallium, nitrogen phosphorus, arsenic, or antimony; and
the stock solutions of Group III-VI elements cadmium, zinc, seleium, tellurium, sulfur, or oxygen.

### Claim 9 (depends on 8)

The method of claim 8, wherein stock solutions of Group III-VI elements consist of indium palmitate and tris-trimethylsilylphosphine.

### Claim 10 (depends on 1)

The method of claim 1, wherein the nanoparticles consist of GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbS, PbSe, PbTe, MN, AlP, AlAs, AlSb, GaN, GaP GaAs, GaSb, InN, InP, InAs, InSb, GaS, GaSe, GaTe, InS, InSe, InTe, TlS, TlSe, TlTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, As2S3, As4S4, As2Se3, As2Te3, Sb2S3, Sb2Se3, Sb2Te3, Bi2S3, Bi2Se3, Bi2Te3, CuO, Cu2O, Ag2S, CuSe, CuCl, AgBr, AuCl, NiS2, PdS, PtSe, CoSe, RhS, IrSe, FeO, FeS, FeSe, RuS, MnO, MnS, MnSe, ReS, Cr2S3, Cr2Se3, MoS2, VS, VSe, NbS, TiO2, TiS2, ZrS2, BeO, MgS, CaSe, or BaTiO3.

### Claim 11

A method of etching nanoparticles comprising the steps of:
providing stock solutions of Group III-VI elements;
providing an ionic liquid containing an anion that thermally degrades to form an ion etchant, wherein the anion is BF4 PF6, F, ClO4, PO4, chloride, bromide, acetate, or hydroxide;
placing the ionic liquid into a microwave reactor vessel;
dissolving the stock solutions of Group III-VI elements in a solute and injecting the resulting solution into the microwave reactor vessel;
subjecting the microwave reactor vessel to an inert atmosphere, wherein the inert atmosphere contacts the stock solutions of Group III-VI elements and the ionic liquid;
subjecting the solutions in the microwave reactor vessel to microwave irradiation, wherein the microwave irradiation degrades the anion of the ionic liquid into an etchant;
where the etchant is F−, Cl−, Br−, or O−;
allowing the stock solutions of Group III-VI elements to form nanoparticles, wherein the nanoparticles are etched in situ by the etchant; and
collecting the resulting nanoparticles.

### Claim 12 (depends on 11)

The method of claim 11, wherein the microwave irradiation is ramped at 300 W.

### Claim 13 (depends on 11)

The method of claim 11, further comprising ramping the reaction between 1 minute and 25 minutes.

### Claim 14 (depends on 11)

The method of claim 11, wherein the ionic liquid comprises 1-hexyl-3-methyl-imidazolium, 1-butyl-4-methyl-pyridinium, tetrabutylammonium, or their derivatives.

### Claim 15 (depends on 11)

The method of claim 11, wherein the ionic liquid is used at a molar concentration ratio between 1:1 and 1:10, stock solutions of Group III-VI elements to ionic liquid.

### Claim 16 (depends on 11)

The method of claim 11, wherein the resulting nanoparticles are collected by using at least one compound selected from the group consisting of toluene, acetone, and methanol.

### Claim 17 (depends on 11)

The method of claim 11, further comprising the step of cooling the reaction site after reaction completion using forced air cooling.

### Claim 18 (depends on 11)

The method of claim 11, wherein stock solutions of Group III-VI elements are compounds selected from the group consisting of indium, gallium, nitrogen phosphorus, arsenic, indium palmitate, tris-trimethylsilylphosphine, and antimony; and
wherein the stock solutions of Group III-VI elements are cadmium, zinc, seleium, tellurium, sulfur, or oxygen.

### Claim 19 (depends on 18)

The method of claim 18, wherein stock solutions of Group III-VI elements further consist of indium palmitate and tris-trimethylsilylphosphine.

### Claim 20 (depends on 11)

The method of claim 11, wherein the nanoparticles consist of GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbS, PbSe, PbTe, AN, AlP, AlAs, AlSb, GaN, GaP GaAs, GaSb, InN, InP, InAs, InSb, GaS, GaSe, GaTe, InS, InSe, InTe, TlS, TlSe, TlTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, As2S3, As4S4, As2Se3, As2Te3, Sb2S3, Sb2Se3, Sb2Te3, Bi2S3, Bi2Se3, Bi2Te3, CuO, Cu2O, Ag2S, CuSe, CuCl, AgBr, AuCl, NiS2, PdS, PtSe, CoSe, RhS, IrSe, FeO, FeS, FeSe, RuS, MnO, MnS, MnSe, ReS, Cr2S3, Cr2Se3, MoS2, VS, VSe, NbS, TiO2, TiS2, ZrS2, BeO, MgS, CaSe, or BaTiO3.