CN109399620B

CN109399620B - Method for preparing high-mobility silicon carbide-based graphene material

Info

Publication number: CN109399620B
Application number: CN201811477126.2A
Authority: CN
Inventors: 刘庆彬; 蔚翠; 何泽召; 高学栋; 郭建超; 周闯杰; 冯志红
Original assignee: CETC 13 Research Institute
Current assignee: CETC 13 Research Institute
Priority date: 2018-12-05
Filing date: 2018-12-05
Publication date: 2020-10-09
Anticipated expiration: 2038-12-05
Also published as: CN109399620A

Abstract

The invention discloses a method for preparing a high-mobility silicon carbide-based graphene material, which comprises the steps of growing the graphene material on a silicon carbide substrate through chemical vapor deposition, introducing a gaseous carbon source, nitrogen and gaseous ethanol by taking hydrogen and argon as carrier gases, and growing for 1-100min at the temperature of 1400 ℃ and 1800 ℃ and the pressure of 500 mbar. The graphene material prepared by the method has low surface wrinkle density, high carrier mobility and low square resistance nonuniformity.

Description

Method for preparing high-mobility silicon carbide-based graphene material

Technical Field

The invention relates to the technical field of graphene material preparation, in particular to a method for preparing a high-mobility silicon carbide-based graphene material.

Background

The mobility is an important parameter reflecting the conductivity of a current carrier in a semiconductor, in a semiconductor material, the current carrier generated due to some reason is in random thermal motion, when a voltage is applied, the current carrier is acted by an electric field force and makes directional motion to form a current, and the higher the mobility is, the faster the current carrier moves, and the higher the conductivity of the semiconductor material is.

Graphene is a two-dimensional hexagonal structure composed of carbon atoms, and can be widely applied to various fields such as nano electronic devices, ultrahigh-speed computer chips, high-efficiency energy storage, solid-state gas sensors, field emission materials, microelectronic integration and the like. Graphene is prepared by a variety of methods, and a Chemical Vapor Deposition (CVD) method is an important means for preparing graphene. In the CVD preparation process, the nucleation density of the graphene is not easy to control, the grain size of the prepared graphene is usually between several hundred nanometers and several hundred micrometers, and the graphene is easy to generate defects in the nucleation and growth processes, so that the mobility and the conductivity are greatly influenced. For example, Chinese patent application 107500278A discloses a growth method for preparing graphene material with low wrinkle density, which can reduce the wrinkle density of the surface of the material to 0.1 piece/mum by adjusting the flow rate of gaseous carbon source in the growth process and the like²However, the mobility is still low and can only reach 5000cm²Approximately V.s.

Disclosure of Invention

Aiming at the problems of low mobility and the like of graphene prepared by CVD in the prior art, the invention provides a method for preparing a high-mobility silicon carbide-based graphene material.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing a high-mobility silicon carbide-based graphene material comprises the steps of growing the graphene material on a silicon carbide substrate through chemical vapor deposition, introducing a gaseous carbon source, nitrogen and gaseous ethanol by taking hydrogen and argon as carrier gases, and growing for 1-100min at the temperature of 1400 plus-one-year 1800 ℃ and the pressure of 500 plus-one-year 1000mbar to obtain the high-mobility silicon carbide-based graphene material.

Preferably, the insulating substrate is cleaned, dried and then placed in chemical vapor deposition equipment, and the equipment is vacuumized until the vacuum pressure is less than or equal to 10 DEG^- ⁴mbar。

Preferably, the cleaning and drying method of the insulating substrate is as follows: the insulating substrate is heated and cleaned by concentrated sulfuric acid, aqua regia and hydrofluoric acid solution respectively, washed by deionized water, dried by a nitrogen gun and then placed in a dustproof device, and dried in an oven.

Preferably, the vacuum environment is heated to 500-1100 ℃ to remove the adsorbed gas on the surface of the substrate.

Preferably, the argon flow is 1-20L/min and the hydrogen flow is 1-20L/min.

Preferably, the gaseous carbon source is methane, ethane, ethylene, acetylene or propane, and the flow rate is 0.001-0.2L/min.

Preferably, the ratio of the flow rates of the gaseous carbon source and the hydrogen gas is between 0.01% and 1%.

Preferably, the flow rate of nitrogen is 0.05-1L/min.

Preferably, the flow rate of the gaseous ethanol is 0.001-1L/min

Preferably, after the growth process is finished, stopping introducing the hydrogen, the gaseous carbon source and the nitrogen, continuously introducing the argon, keeping the pressure unchanged, and reducing the temperature to room temperature in an argon environment.

According to the method, in the growth process of the graphene, gaseous ethanol is introduced, and is decomposed into hydrocarbon and water at high temperature, and the hydrocarbon and the water interact with the gaseous carbon source to influence the decomposition rate of the gaseous carbon source, control the nucleation density of the graphene, adjust the overall growth consistency of the graphene material, effectively reduce the surface wrinkle density of the material, avoid the generation of defects such as holes in the nucleation and growth processes, and improve the carrier mobility, so that the crystal quality and the electrical characteristics of the graphene material are improved. The graphene material grown on the silicon carbide substrate by the CVD method is single-layer P-type doped graphene, and has the advantages of no need of substrate transfer, good crystal quality, excellent electrical characteristics and easy combination with a Si-based semiconductor process.

Detailed Description

In order to better explain the technical scheme of the invention, the following examples are further illustrative.

Example 1

Selecting a SiC substrate, respectively heating and cleaning the SiC substrate by concentrated sulfuric acid, aqua regia and hydrofluoric acid solution, flushing the SiC substrate by deionized water, blowing the SiC substrate by a nitrogen gun, then placing the SiC substrate in a dustproof device, and drying the SiC substrate in an oven. Putting the cleaned and dried SiC substrate into CVD equipment, and vacuumizing to be less than or equal to 10^-4mbar, turning on a microwave power supply, heating to 1100 deg.C in vacuum environment, and removing adsorbed gas on the surface of the substrate. Introducing hydrogen and argon into the reaction furnace as carrier gas, introducing propane as gaseous carbon source, introducing nitrogen and gaseous ethanol, wherein the flow rate of the argon is 3L/min, the flow rate of the propane is 0.022L/min, the flow rate of the hydrogen is 10L/min, the C/H ratio is 0.22%, the flow rate of the nitrogen is 0.2L/min, the flow rate of the gaseous ethanol is 0.02L/min, the growth temperature is 1450 ℃, the growth pressure is 900mbar, and the growth time is 95 min. And after the growth is finished, closing the microwave power supply, stopping hydrogen, the gaseous carbon source and nitrogen, continuously introducing argon, keeping the pressure at 900mbar unchanged, and reducing the pressure to room temperature in an argon environment. The prepared graphene material is 1 layer, and the fold density is less than 0.1 per mu m²The half-height width of the graphene Raman 2D peak is less than or equal to 30cm^-1The mobility of the graphene is more than or equal to 6,000cm²The square resistance nonuniformity is less than or equal to 5 percent.

Examples 2 to 3

The control conditions of examples 2 to 3 are shown in the following table, and the parts not described are the same as those of example 1.

Condition	Example 2	Example 3
			Carbon source	Methane	Ethylene
Temperature (. degree.C.)	1400	1750
			Pressure (mbar)	800	500
Time (min)	50	5
			Argon flow (L/min)	18	10
Carbon source flow (L/min)	0.2	0.001
			Hydrogen flow (L/min)	20	2
C/H ratio	1％	0.05％
			Nitrogen flow (L/min)	0.95	0.05
Flow rate of gaseous ethanol (L/min)	0.9	0.002

The graphene materials prepared in the examples 2 and 3 are respectively 3 layers and 1 layer, and the fold density is less than 0.1 piece/mum²The half-height width of the graphene Raman 2D peak is less than or equal to 30cm^-1The mobility of the graphene is more than or equal to 6,000cm²The square resistance nonuniformity is less than or equal to 5 percent.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a high-mobility silicon carbide-based graphene material is characterized by comprising the following steps: growing a graphene material on a silicon carbide substrate by chemical vapor deposition, introducing a gaseous carbon source, nitrogen and gaseous ethanol by taking hydrogen and argon as carrier gases, and growing for 1-100min at the temperature of 1400-plus-one 1800 ℃ and the pressure of 500-plus-one 1000mbar to prepare the high-mobility silicon carbide-based graphene material;

the gaseous carbon source is methane, ethane, ethylene, acetylene or propane, and the flow rate of the gaseous carbon source is 0.001-0.2L/min;

the flow rate of the nitrogen is 0.05-1L/min;

the flow rate of the gaseous ethanol is 0.001-1L/min;

and after the growth process is finished, stopping hydrogen, the gaseous carbon source and nitrogen, introducing argon, keeping the pressure unchanged, and cooling to room temperature in an argon environment.

2. The method of preparing a high mobility silicon carbide-based graphene material according to claim 1, wherein: cleaning and drying the insulating substrate, putting the insulating substrate into chemical vapor deposition equipment, and vacuumizing to less than or equal to 10^-4mbar。

3. The method of preparing a high mobility silicon carbide-based graphene material according to claim 2, wherein: the cleaning and drying method of the insulating substrate comprises the following steps: the insulating substrate is heated and cleaned by concentrated sulfuric acid, aqua regia and hydrofluoric acid solution respectively, washed by deionized water, dried by a nitrogen gun and then placed in a dustproof device, and dried in an oven.

4. The method of preparing a high mobility silicon carbide-based graphene material according to claim 3, wherein: the vacuum environment is heated to 500-1100 ℃ to remove the adsorbed gas on the surface of the substrate.

5. The method of preparing a high mobility silicon carbide-based graphene material according to claim 1, wherein: the argon flow is 1-20L/min, and the hydrogen flow is 1-20L/min.

6. The method of preparing a high mobility silicon carbide-based graphene material according to claim 1, wherein: the C/H ratio is 0.01-1%, and the C/H ratio is the ratio of the flow rates of the gaseous carbon source and the hydrogen.