# US 2022/0033261 A1 · Method for making transition metal dichalcogenide crystal

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- Number: US 2022/0033261 A1
- Document ID: US20220033261A1
- Status: Published application
- Kind: A1
- Application number: 17/328,227
- Filed: 2021-05-24
- Published: 2022-02-03
- Earliest claimed: 2020-07-31
- Assignees: Tsinghua University; Hon Hai Precision Industry Co., Ltd.
- Applicants: Tsinghua University; Hon Hai Precision Industry Co., Ltd.
- Inventors: HAO LI; YANG WU; SHOU-SHAN FAN
- Web page: https://patentgrep.com/patent/US20220033261A1

## CPC

- C01B 19/007: {Tellurides or selenides of metals (C01B19/002 takes precedence)}
- C30B 23/00: Single-crystal growth by condensing evaporated or sublimed materials
- C30B 25/08: Reaction chambers; Selection of materials therefor
- C30B 29/46: Sulfur-, selenium- or tellurium-containing compounds
- C30B 29/48: AIIBVI compounds {wherein A is Zn, Cd or Hg, and B is S, Se or Te}
- C01P 2002/72: by d-values or two theta-values, e.g. as X-ray diagram
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- 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
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

A method for making a transition metal dichalcogenide crystal having a chemical formula represented as MX2 is provided, wherein M represents a central transition metal element, and X represents a chalcogen element. The method includes providing a MX2 polycrystalline powder, a MX2 seed crystal, and a transport medium. The MX2 polycrystalline powder and the transport medium are placed in a first reaction chamber. The first reaction chamber and the MX2 seed crystal are placed in a second reaction chamber having a source end and a deposition end opposite to the source end. The first reaction chamber is placed at the source end, and the MX2 seed crystal is placed at the deposition end.

## Claims

### Claim 1

A method of making a transition metal dichalcogenide crystal having a chemical formula represented as MX2, wherein M represents a central transition metal element, and X represents a chalcogen element, comprising:
providing MX2 polycrystalline powder, MX2 seed crystals, and a transport medium;
providing a first reaction chamber defining an opening at one end of the first reaction chamber, wherein the MX2 polycrystalline powder and the transport medium are placed in the first reaction chamber; and
providing a second reaction chamber comprising a source end and a deposition end opposite to the source end, wherein the first reaction chamber and the MX2 seed crystals are placed in the second reaction chamber, the first reaction chamber is placed at the source end, and the MX2 seed crystals are placed at the deposition end.

### Claim 2 (depends on 1)

The method of claim 1, wherein the MX2 polycrystalline powder is obtained by direct solid-state reactions of a mixture of the central transition metal element M and the chalcogen element X.

### Claim 3 (depends on 1)

The method of claim 1, wherein the MX2 seed crystals comprise a plurality of single crystals.

### Claim 4 (depends on 3)

The method of claim 3, wherein average sizes of the MX2 seed crystals are in a range from 500 μm to 1 mm.

### Claim 5 (depends on 1)

The method of claim 1, wherein a method for providing the MX2 seed crystals comprises:
placing the MX2 polycrystalline powder and the transport medium in a chamber configured for chemical vapor transport (CVT) growing, to obtain MX2 crystals;
removing remaining transport medium in the MX2 crystals; and
selecting the MX2 crystals with sizes in a range of 500 microns to 1 mm for making the transition metal dichalcogenide crystal.

### Claim 6 (depends on 5)

The method of claim 5, further comprising cutting the selected MX2 crystals to form a hexagon, a triangle, or a square.

### Claim 7 (depends on 1)

The method of claim 1, wherein the opening of the first reaction chamber is away from the MX2 seed crystals.

### Claim 8 (depends on 1)

The method of claim 1, wherein the first reaction chamber is spaced apart from the MX2 seed crystals.

### Claim 9 (depends on 1)

The method of claim 1, wherein the MX2 polycrystalline powder and the transport medium are away from the opening of the first reaction chamber.

### Claim 10 (depends on 1)

The method of claim 1, wherein a distance between the MX2 polycrystalline powder and the opening is in a range from about 2 cm to about 6 cm.

### Claim 11 (depends on 1)

The method of claim 1, wherein TH represents a temperature at the opening of the first reaction chamber, TS represents a temperature of the MX2 polycrystalline powder, and TD represents a temperature at the deposition end of the second reaction chamber; and −15 K<(TS−TH)<−5 K, 45 K<(TH−TD)<55 K.

### Claim 12

A method for making a transition metal dichalcogenide crystal having a chemical formula represented as MX2, wherein M represents a central transition metal element, and X represents a chalcogen element; and the method for making the transition metal dichalcogenide crystal, comprising:
placing a MX2 polycrystalline powder and a transport medium in a first reaction chamber; and
placing the first reaction chamber and a MX2 seed crystal in a second reaction chamber having a source end and a deposition end opposite to the source end, wherein the first reaction chamber is placed at the source end, and the MX2 seed crystal is placed at the deposition end, and the first reaction chamber and the MX2 seed crystal are spaced apart from each other.

### Claim 13 (depends on 12)

The method of claim 12, wherein the MX2 polycrystalline powder is obtained by direct solid-state reaction of a mixture of M element and X element.

### Claim 14 (depends on 12)

The method of claim 12, wherein the MX2 seed crystal is a single crystal.

### Claim 15 (depends on 14)

The method of claim 14, wherein a size of the MX2 seed crystal is in a range from 500 μm to 1 mm.

### Claim 16 (depends on 12)

The method of claim 12, wherein a method for making the MX2 seed crystal comprises:
placing the MX2 polycrystalline powder and the transport medium in a chamber for CVT growing, to obtain a MX2 crystal;
removing remaining transport medium in the MX2 crystal; and
selecting the MX2 crystal with a size range of 500 microns to 1 mm as the MX2 seed crystal.

### Claim 17 (depends on 16)

The method of claim 16, further comprising a step of cutting the MX2 crystal to form a hexagon, a triangle, or a square, after selecting the MX2 crystal with the size range of 500 microns to 1 mm as the MX2 seed crystal.