# US 2014/0190837 A1 · Electrochemical liquid-liquid-solid deposition processes for production of group iv semiconductor materials

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- Number: US 2014/0190837 A1
- Document ID: US20140190837A1
- Status: Published application
- Kind: A1
- Application number: 14/234,084
- Filed: 2012-07-20
- Published: 2014-07-10
- Earliest claimed: 2011-07-22
- Assignees: The Regents of the University of Michigan
- Inventors: Stephen Maldonado; Azhar Carim
- Web page: https://patentgrep.com/patent/US20140190837A1

## CPC

- C25B 1/33: Silicon
- C25C 1/22: of metals not provided for in groups C25C1/02 - C25C1/20
- C30B 7/12: by electrolysis
- C30B 29/06: Silicon
- C30B 29/08: Germanium
- C30B 29/52: Alloys
- H10P 14/265: {using solutions}
- H10P 14/274: {using seed materials}
- H10P 14/279: {Vapour-liquid-solid growth}
- H10P 14/2923: {being conductive materials, e.g. metallic silicides}
- H10P 14/3411: {Silicon, silicon germanium or germanium}
- H10P 14/3462: {Nanowires}
- C25B: ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR (anodic or cathodic protection C23F13/00; single-crystal growth C30B)
- C25C: PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- 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
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

An electrochemical liquid-liquid-solid (LLS) process that produces unlimited amounts of crystalline semiconductor, such as Ge or Si, from aqueous or polar solutions with tunable nanostructured shapes without any physical or chemical templating agent is presented. Dissolution into, saturation within, and precipitation of the semiconductor from a liquid electrode (e.g., Hg pool) or near an electrode comprising metallic nanoparticles (e.g., In nanoparticles) yields a polycrystalline semiconductor material, as deposited. Such a process can be conducted at conditions, in a single step, and under electrochemical control, while affording control over formation of a variety of material morphologies. Materials formed by such processes are also provided.

## Claims

### Claim 1

A method comprising:
contacting a liquid electrolyte with a first electrode, wherein the first electrode is in electrical communication with a second electrode having a second opposite polarity from the first electrode, wherein the liquid electrolyte is formed by combining water and an oxide compound of a semiconductor element selected from the group consisting of: silicon, germanium, and combinations thereof; and
generating a precipitated solid material comprising the semiconductor element by applying an electric potential to the first electrode in contact with the electrolyte to drive an electrochemical reduction reaction that forms a solid material comprising the semiconductor element by precipitation out of solution at or within the first electrode.

### Claim 2 (depends on 1)

The method of claim 1, wherein the solid material is crystalline and comprises silicon and the first electrode comprises a material that is inactive with respect to any parasitic electrolyte decomposition electrochemical reaction in the presence of the semiconductor element.

### Claim 3 (depends on 2)

The method of claim 2, wherein the oxide compound comprises silicon dioxide (SiO2) and the first electrode comprises mercury or indium, so as to form the crystalline solid material.

### Claim 4 (depends on 1)

The method of claim 1, wherein the solid material comprises silicon and the generating occurs by dissolving the silicon into the first electrode, followed by saturating the first electrode with the dissolved silicon, and then precipitating the silicon from the first electrode.

### Claim 5 (depends on 1)

The method of claim 1, wherein the solid material comprises germanium and the first electrode comprises a material that is inactive with respect to any parasitic electrolyte decomposition electrochemical reaction in the presence of the semiconductor element, so that the generating occurs by dissolving the germanium in the first electrode, followed by saturating the first electrode with the dissolved germanium, and then precipitating the germanium from the first electrode.

### Claim 6 (depends on 5)

The method of claim 5, wherein the oxide compound comprises germanium oxide (GeO2) and the first electrode comprises mercury or indium.

### Claim 7 (depends on 1)

The method of claim 1, wherein the rate of generating the precipitated solid material comprising the semiconductor element is determined by magnitude of the applied electric potential.

### Claim 8 (depends on 1)

The method of claim 1, wherein the rate of generating the precipitated solid material comprising the semiconductor element is greater than or equal to about 1×10−12 mol cm−2 s−1.

### Claim 9 (depends on 1)

The method of claim 1, wherein the applied electric potential is greater than or equal to about a standard potential for the semiconductor reduction process to less than or equal to about 2 V overpotential.

### Claim 10 (depends on 1)

The method of claim 1, wherein the first electrode comprises a metal selected from the group consisting of: mercury, gallium, indium, and alloys and combinations thereof.

### Claim 11 (depends on 1)

The method of claim 1, wherein the generating is conducted at greater than or equal to room temperature to less than or equal to about 100° C.

### Claim 12

A method for forming a crystalline material comprising:
contacting a liquid electrolyte with a first liquid electrode, wherein the first liquid electrode is in electrical communication with a second electrode having a second opposite polarity from the first liquid electrode, wherein the liquid electrolyte is formed by combining water and an oxide compound comprising a Group IV semiconductor element, and wherein the first liquid electrode comprises a metal selected from the group consisting of: mercury, gallium, indium, zinc, cadmium, combinations and alloys thereof; and
generating a crystalline material comprising the Group IV semiconductor element by applying an electric potential to the first liquid electrode in contact with the electrolyte to drive an electrochemical reduction reaction that generates the crystalline material comprising the Group IV semiconductor element by precipitation at or within the first liquid electrode.

### Claim 13 (depends on 12)

The method of claim 12, wherein the generating occurs by dissolving the Group IV semiconductor element in the first liquid electrode, followed by saturation of the first liquid electrode with the Group IV semiconductor element, and then precipitating the Group IV semiconductor element from the first liquid electrode.

### Claim 14 (depends on 12)

The method of claim 12, wherein the Group IV semiconductor element is selected from the group consisting of: germanium, silicon, and combinations thereof.

### Claim 15 (depends on 12)

The method of claim 12, wherein the oxide compound is selected from either germanium oxide (GeO2) or silicon dioxide (SiO2).

### Claim 16 (depends on 12)

The method of claim 12, wherein the crystalline material is a polycrystalline material.

### Claim 17 (depends on 16)

The method of claim 16, wherein the polycrystalline material has an average crystal domain size of greater than or equal to about 10 nanometers to less than or equal to about 500 micrometers, wherein domains in the polycrystalline material are randomly oriented.

### Claim 18 (depends on 12)

The method of claim 12, wherein the crystalline material is a single crystal material.

### Claim 19 (depends on 12)

The method of claim 12, further comprising controlling the morphology of the crystalline material by the applied electric potential applied to generate a polycrystalline material in the shape of filaments, cubes, or sheets.

### Claim 20

A polycrystalline material comprising:
a precipitated solid comprising a semiconductor element selected from the group consisting of: silicon, germanium, and combinations thereof having randomly oriented crystal domains, wherein an average crystal domain size is greater than or equal to about 5 nanometers.

### Claim 21 (depends on 20)

The polycrystalline material of claim 20 in the form of a filament, a cube, or a sheet.

### Claim 22 (depends on 20)

The polycrystalline material of claim 20, wherein the average crystal domain size is greater than or equal to about 5 nanometers to less than or equal to about 10 micrometers.

### Claim 23 (depends on 20)

An electrochemical cell comprising an electrode comprising the polycrystalline material of claim 20, wherein the semiconductor element comprises germanium.