阅读说明：本技术 生长单层磷化硅晶体的方法 (Method for growing single-layer silicon phosphide crystal ) 是由 邱海龙 武羽 胡章贵 于 2020-04-20 设计创作，主要内容包括：本发明公开了一种生长单层磷化硅晶体的方法,包括以下步骤：准备石英管,石英管的两端分别为原料端和基底端,在石英管的基底端内放置一基底,在石英管的原料端内放置原材料和输运剂,对石英管进行抽真空,抽真空后密封石英管,其中,原材料为单质硅和红磷的混合物,输运剂为单质碘；对石英管的原料端和基底端同时加热5～36h,加热后随炉冷却至室温20～25℃,在基底上得到单层磷化硅晶体,其中,原料端的加热温度为1000～1150℃,基底端的加热温度为600～950℃。本发明利用化学气相输运法第一次实现了单层磷化硅二维晶体的生长,既是生长单层SiP二维晶体的巨大突破,也为化学气相输运法生二维晶体材料提供有利支撑。(The invention discloses a method for growing single-layer silicon phosphide crystals, which comprises the following steps: preparing a quartz tube, wherein two ends of the quartz tube are respectively a raw material end and a substrate end, placing a substrate in the substrate end of the quartz tube, placing a raw material and a transport agent in the raw material end of the quartz tube, vacuumizing the quartz tube, and sealing the quartz tube after vacuumizing, wherein the raw material is a mixture of elemental silicon and red phosphorus, and the transport agent is elemental iodine; and simultaneously heating the raw material end and the substrate end of the quartz tube for 5-36 hours, cooling the raw material end and the substrate end to room temperature of 20-25 ℃ along with the furnace after heating, and obtaining a single-layer silicon phosphide crystal on the substrate, wherein the heating temperature of the raw material end is 1000-1150 ℃, and the heating temperature of the substrate end is 600-950 ℃. The invention realizes the growth of the monolayer silicon phosphide two-dimensional crystal for the first time by utilizing the chemical vapor transport method, which is a great breakthrough in the growth of the monolayer SiP two-dimensional crystal and provides a favorable support for the chemical vapor transport method to produce the two-dimensional crystal material.)

1. A method for growing a single layer of silicon phosphide crystal, comprising the steps of:

1) preparing a quartz tube, wherein two ends of the quartz tube are respectively a raw material end and a substrate end, placing a substrate in the substrate end of the quartz tube, placing a raw material and a transport agent in the raw material end of the quartz tube, vacuumizing the quartz tube, and sealing the quartz tube after vacuumizing so that the pressure in the quartz tube is 4 × 10^-6～4×10^-4Pa, wherein the raw material is a mixture of elemental silicon and red phosphorus, and the transport agent is elemental iodine;

2) and simultaneously heating the raw material end and the substrate end of the quartz tube for 5-36 hours, cooling the heated raw material end and the substrate end to room temperature of 20-25 ℃ along with the furnace, and obtaining a single-layer silicon phosphide crystal on the substrate, wherein the heating temperature of the raw material end is 1000-1150 ℃, and the heating temperature of the substrate end is 600-950 ℃.

2. The method as recited in claim 1, wherein in the step 1), the ratio of the elemental silicon to the red phosphorus is (1-6): 1 in parts by mass.

3. The method of claim 2, wherein in step 1), the substrate is sapphire.

4. The method according to claim 3, wherein in the step 1), the quartz tube has a length of 15 to 50cm and an inner diameter of 10 to 20 mm.

5. The method according to claim 4, wherein in the step 1), the ratio of the raw material to the transport agent is (2-6) in parts by mass: (1-3).

6. The method according to claim 5, wherein the mass of the raw material is 2-6 mg.

7. The method according to claim 6, wherein in the step 2), the temperature gradient between the raw material end and the substrate end is 1.6-14 ℃/cm.

Technical Field

The invention belongs to the technical field of preparation of single-layer silicon phosphide crystals, and particularly relates to a method for growing single-layer silicon phosphide crystals.

Background

The two-dimensional materials known at present have the advantages and disadvantages, such as high thermal conductivity and high carrier mobility of grapheneHowever, the zero band gap of graphene makes the graphene incapable of realizing the logic switch of a semiconductor, thereby greatly limiting the application of the graphene in the field of semiconductors; molybdenum disulfide is taken as a typical transition metal chalcogenide two-dimensional semiconductor compound, a monolayer of which has a direct band gap of 1.8eV, so that the molybdenum disulfide is not restricted by a zero band gap, and the current switching ratio of the molybdenum disulfide is as high as 10⁸However, the room temperature carrier mobility of the material is only 200cm²v^-1s^-1Too low mobility limits its application in the semiconductor field. Therefore, finding a two-dimensional semiconductor material with a suitable band gap, high carrier mobility and more stability is still an important research subject in the field of two-dimensional materials. The silicon phosphide crystal is a typical representative of a novel two-dimensional material IVA-VA, has excellent anisotropic characteristics and photoelectric properties, and has great application potential in a plurality of fields such as microelectronics, energy, catalysis, nonlinear optics and the like.

Two-dimensional silicon phosphide crystals are usually obtained by a mechanical stripping method, but the two-dimensional silicon phosphide crystals with controllable layer number and size are difficult to obtain, and the yield is low. It is difficult to prepare by the conventional two-dimensional crystal growth method because of its unstable physicochemical properties. The thin-layer silicon phosphide crystal prepared by the liquid phase stripping method is easy to pollute a sample, the property of the sample is easy to change, and the thickness is not easy to control in the transverse direction and the longitudinal direction; because phosphorus has higher saturated vapor pressure and silicon has higher melting point, the preparation of the silicon phosphide crystal by using a Chemical Vapor Deposition (CVD) method is difficult to realize; the cost for preparing silicon phosphide crystals by film epitaxy is high; the Physical Vapor Deposition (PVD) method for preparing the silicon phosphide crystals can be synthesized, but firstly, the raw material synthesis steps are complex, and secondly, impurities are easily introduced.

Disclosure of Invention

Aiming at the problem of difficulty in preparing two-dimensional silicon phosphide crystals, the invention aims to provide a method for growing single-layer silicon phosphide crystals, which can prepare single-layer silicon phosphide crystals in one step by improving the traditional Chemical Vapor Transport (CVT) method for growing crystals.

The purpose of the invention is realized by the following technical scheme.

A method of growing a single layer of silicon phosphide crystal comprising the steps of:

1) preparing a quartz tube, wherein two ends of the quartz tube are respectively a raw material end and a substrate end, placing a substrate in the substrate end of the quartz tube, placing a raw material and a transport agent in the raw material end of the quartz tube, vacuumizing the quartz tube, and sealing the quartz tube after vacuumizing so that the pressure in the quartz tube is 4 × 10^-6～4×10^-4Pa, wherein the raw material is a mixture of elemental silicon and red phosphorus, and the transport agent is elemental iodine;

in the step 1), the substrate is sapphire.

In the step 1), the length of the quartz tube is 15-50 cm, and the inner diameter is 10-20 mm.

In the step 1), the ratio of the raw materials to the transport agent is (2-6) in parts by mass: (1-3).

In the technical scheme, the mass of the raw material is 2-6 mg.

In the step 1), the ratio of the simple substance silicon to the red phosphorus is (1-6): 1 in parts by mass.

2) And simultaneously heating the raw material end and the substrate end of the quartz tube for 5-36 hours, cooling the heated raw material end and the substrate end to room temperature of 20-25 ℃ along with the furnace, and obtaining a single-layer silicon phosphide crystal on the substrate, wherein the heating temperature of the raw material end is 1000-1150 ℃, and the heating temperature of the substrate end is 600-950 ℃.

In the step 2), the temperature gradient between the raw material end and the substrate end is 1.6-14 ℃/cm.

The invention realizes the growth of the monolayer silicon phosphide (SiP) two-dimensional crystal for the first time by utilizing the chemical vapor transport method, which is a great breakthrough for the growth of the monolayer SiP two-dimensional crystal and provides a favorable support for the chemical vapor transport method to produce the two-dimensional crystal material.

Drawings

FIG. 1 is an optical micrograph of a single-layer silicon phosphide crystal obtained in example 1 of the present invention;

FIG. 2 is a photograph taken by an Atomic Force Microscope (AFM) of a single-layer silicon phosphide crystal obtained in example 1 of the present invention;

FIG. 3 shows a Raman spectrum of a single-layer silicon phosphide crystal obtained in example 1 of the present invention.

Detailed Description

The technical scheme of the invention is further explained by combining specific examples.

Elemental silicon (Si): purity is more than or equal to 99.999 percent and Alfa Aesar

Red phosphorus (P): purity is more than or equal to 99.999 percent and Alfa Aesar

Elemental iodine (I)₂): purity is more than or equal to 99.999 percent and Alfa Aesar

OLYMPUS-bx53 m-microscope

WiTec confocal Raman and atomic force microscope system (Raman-AFM)

Because the phosphorus simple substance has higher saturated vapor pressure and the silicon simple substance has higher melting point, the synthesis is carried out in a closed container, the CVT method can realize closed and high-vacuum reaction, and the preparation of the silicon phosphide is accurately controlled by adjusting thermodynamic and kinetic influencing factors.