WO2017041401A1 - Rapid growth of large single-crystal graphene assisted by adjacent oxide substrate - Google Patents
Rapid growth of large single-crystal graphene assisted by adjacent oxide substrate Download PDFInfo
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- WO2017041401A1 WO2017041401A1 PCT/CN2016/000282 CN2016000282W WO2017041401A1 WO 2017041401 A1 WO2017041401 A1 WO 2017041401A1 CN 2016000282 W CN2016000282 W CN 2016000282W WO 2017041401 A1 WO2017041401 A1 WO 2017041401A1
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- C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
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- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
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Abstract
Disclosed here is a method for rapid growth of large single-crystal graphene assisted by adjacent oxide substrate with chemical vapour deposition system under atmospheric pressure, wherein metal foils are naturally placed on oxide substrates with very narrow spaces between them. O released from the oxide substrates at high temperature could diffuse to the metal surface and involve in the catalytic reactions on the surface of metal foils. This would drastically lower the barrier of the feedstock decomposition and increase the carbon species supply by orders of magnitude, which enables the rapid growth. This method solves a lot of problems in the field of large single-crystal graphene growth， such as expensive monocrystalline substrates, complex pre-treatment of metal foils and a rather long growth cycle. Thus our technique realizes the synthesis of large single-crystal in a very short time and with an efficient cost.
Description
The present invention relates generally to the field of a method of the growth of large single-crystal graphene， and more particularly to a method for rapid growth of large single-crystal graphene assisted by oxide substrate.
Graphene， a kind of two-dimensional (2D) atomic materials with carbon atoms bonded in a compact honeycomb structure， has attracted intense interests due to its exotic physical properties， including electronic， optoelectronic， mechanic and thermal properties， and been demonstrated to have varying potential applications in many fields. However， many high-end applications of graphene are still stuck in a premature stage， lacking an efficient way to prepare large single-crystal graphene with high quality. Currently， chemical vapour deposition (CVD) growth of graphene on catalytic copper (Cu) foil is the most favourable technique to synthesize graphene because it is simple， cost-efficient and the synthesized graphene always possesses high quality. However， by the CVD method on Cu foils， as-synthesized graphene samples are always polycrystalline， consisting of many single-crystal graphene domains with different orientations and grain boundaries which degrade the properties significantly. Therefore， to achieve high-quality graphene， controlled synthesis of large single-crystal graphene will remain the ultimate challenge in the growth community. For now， the main strategy used to increase the graphene domains size is to reduce the nucleation density by following two methods. The first approach requires surface treatment before the growth to reduce the active sites for the nucleation. However， this approach always involves complex and long-time surface treatment and thus leads to great increase of cost. The second approach is to feed extremely low carbon source to elevate the energy barrier for the nucleation， while this inevitably leads to extremely low graphene growth rate and thus great time and energy cost. The existing methods can’t tackle the
issue very well. Besides， one fact should be noticed that the nucleation is a probability event， meaning that as the time goes on it is unavoidable that new nuclei form during the growth. By reducing the nucleation density only can’t achieve large single-crystal graphene if the growth time is very long. Consequently， suppression of nucleation and improvement of growth rate are the two complementary requests for the synthesis of large single-crystal graphene. Hence optimizing current CVD methods and seeking for an effective strategy that can not only decrease the nucleation density but also increase the growth rate is of significant importance for commercial production and the practical application of graphene.
Summary of the invention
As an aspect of the invention， disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the metal foils are placed on an oxide substrate and the large single-crystal graphene domains are grown on the back side of metal foils facing the oxide substrate. The metal foils are the commercial ones without any pre-treatment.
As an aspect of the invention， disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the growth comprises：
(1) The metal foils are placed on oxide substrates and then loaded into the chemical vapour deposition (CVD) system；
(2) The metal foils are heated to 900 ～ 1100 ℃ under an inert atmosphere. Then the annealing process starts with 0.2 ～ 500 sccm H2；
(3) The CH4 (0.5 ～ 50 sccm) is introduced as carbon source and the growth process lasts for 1 s ～60 min；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature.
As an aspect of the invention， disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the growth comprises：
(1) The metal foils without any pre-treatment are placed on oxide substrates and then loaded into
the chemical vapour deposition (CVD) system；
(2) The metal foils are heated to 900 ～ 1100 ℃ under an inert atmosphere (Ar flow ＞ 300 sccm) in 50 ～ 70 min. Then the annealing process starts with 2 ～ 50 sccm H2 and lasts for 30 ～ 100 min；
(3) After the annealing process， the CH4 gas (0.5 ～ 50 sccm) is introduced as carbon source and the growth process lasted for 1 s ～ 60 min. The H2 flow is tuned to 0.2 ～ 50 sccm；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
The oxide substrates are made of at least one of the following materials： quartz， fused silica， mica， Al2O3， CaO， ZrO， MgO， Cr2O3 or other high temperature oxides. The metal foils are made of at least one of the following materials： copper (Cu) ， platinum (Pt) or gold (Au) . H2 is not introduced to the system during heating process. The system is under atmospheric pressure during heating， annealing， growth and cooling process. The flow of CH4 is 0.5 ～ 50 sccm and H2 is 0.2 ～ 50 sccm. The flow ratio of CH4 and H2 is 0.01 ～ 100. The oxide substrate adheres to the substrate oxide with very narrow space at high temperature. The O released from the oxide could diffuse to the metal surface and involve in the catalytic reaction. This would drastically lower the barrier of the feedstock decomposition and increase the carbon species supply by orders of magnitude， which enables the rapid growth of graphene. Also， the active sites for nucleation could be killed by O， resulting in the decrease of the nucleation density. The shape of the single graphene domains is circular or hexagonal with the diameter ＞ 0.2 mm. The metal foils can be placed on the oxide substrate statically or dynamically. Combined with the roll-to-roll technique， this method can also be used to continuously grow super-large graphene films with large single-crystal graphene domains with domain size larger than 0.2 mm.
As an aspect of the invention， disclosed is a kind of large single-crystal graphene， wherein the growth is carried out with above methods. The shape of the single graphene domains is circular or hexagonal with the diameter ＞ 0.2 mm.
As an aspect of the invention， disclosed is a method for rapid growth of large single-crystal graphene applying atmospheric pressure chemical vapour deposition assisted by oxide substrates， wherein the metal foils are placed on an oxide substrate tightly with very narrow space. The O released from the oxide substrate at high temperature could diffuse to the metal surface. This would drastically lower the barrier of the feedstock decomposition and increase the carbon species supply by orders of magnitude， which enables the rapid growth. This method solves a lot of problems in large single-crystal graphene growth community such as the expensive monocrystalline substrate， complex pre-treatment of metal foils and the rather long growth cycle. Thus this technique realizes the synthesis of large single-crystal graphene in very short time and with efficient cost.
The benefits of this method：
(1) The metal foils are the commercial ones and need no any pre-treatment， which simplifies the growth process， shortens the growth cycle and greatly reduces the cost.
(2) The metal foils are naturally placed on the oxide substrate without any other treatment.
(3) This invention first claims an efficient method to improve CH4 decomposition： the metal foils are placed on an oxide substrate naturally with very narrow space between them. The O released from the oxide substrate at high temperature could diffuse to the metal surface and involve in the catalytic reaction. This would drastically lower the barrier of the feedstock decomposition and increase the carbon species supply by orders of magnitude， which enables the rapid growth. Also， the active sites for nucleation could be killed by O， resulting in the decrease of the nucleation density.
(4) This invention claims a method to synthesize large single-crystal graphene. The graphene domains prepared have large domain size and high quality， which can be applied in the many high-end applications， like electronics and photonics.
(5) This invention is simple and effective， which benefits the practical application of large single-crystal graphene in industry.
Brief description of the figures
Fig. 1 illustrates the schematics of our experimental design. The Cu foil is placed on an oxide substrate naturally.
Fig. 2 is the optical image of the domains of synthesized large single-crystal graphene.
Fig. 3 is the Raman spectrum of the graphene sample， indicating the high quality thereof.
Fig. 4 (b) - (d) are the selected area electron diffraction (SAED) patterns of the grapheme samples shown in Fig. 4 (a) and Fig. 4 (f) - (h) are the low energy electron diffraction (LEED) patterns of the graphene sample shown in Fig. 4 (e) .
Fig. 5 (a) gives the schematics of the gas flow during the growth process with oxide as the substrate and Fig. 5 (b) - (e) show that the graphene domains grown on back side of the Cu foil with oxide substrate and with non-oxide substrate exhibit different morphology.
Fig. 6 illustrates the schematics of the setup combined with roll-to-roll technique.
Detailed description of preferred embodiments
In following embodiments， unless otherwise defined， all raw materials can be obtained by commercial ways. For example， the Cu foils can be obtained from Alfa Aesar with 25 μm thick. Then they are cut into little pieces to be loaded into the CVD system.
First embodiment
Disclosed here is a method for rapid growth of large single-crystal graphene assisted by oxide substrate.
This method is carried out using the setup shown in Fig. 1. As is shown in Fig. 1， Cu foils are naturally placed on the top of oxide substrate in a CVD system. The steps of the growth comprise：
(1) The metal foils are placed on oxide substrates without any pre-treatment and then loaded into the chemical vapour deposition (CVD) system；
(2) The metal foils are heated to 900 ～ 1100 ℃ under an inert atmosphere (Ar flow ＞ 300 sccm) in 50～ 70 min. Then the annealing process starts with 2 ～ 50 sccm H2 and lasts for 30 ～ 100 min；
(3) After the annealing process， the CH4 gas (0.5 ～ 50 sccm) is introduced as carbon source and the growth process lasts for 1 s ～ 60 min. The H2 flow is tuned to 0.2 ～ 50 sccm；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
To be sure， if the surfaces of the metal foils are cleaned with some pre-treatments， large single-crystal graphene could also be obtained.
The pressure of the system is atmospheric， i.e. 1 × 105 Pa.
The benefits of this method include：
(1) The metal foils are the commercial metal foils and the growth experiments have high repetition rate.
(2) The metal foils could be naturally placed on the common oxide substrate without any mechanical treatment.
(3) The growth process lasts just for 1 s ～ 60 min， which is very short and cost-effective.
(4) The graphene prepared herein has large domain size and high quality， which possess potential applications in many fields， such as electronics and photonics.
Following detailed experiments are carried out to verify the beneficial effects of the invention：
Experiment 1： Disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide
substrate， wherein the steps of growth comprise：
(1) Cu foils without any pre-treatment are placed on Al2O3 substrate and then loaded into a chemical vapour deposition (CVD) system；
(2) The system is heated to 1000 ℃ under an inert atmosphere， for example， Ar with a flow rate of 300 sccm， in 60 min. Then the annealing process starts with 5 sccm H2 and lasts for 40 min；
(3) After the annealing process， the CH4 (5 sccm) is introduced as carbon source and the growth process lasts for 2 min. The H2 flow is not tuned and remained the same as in step (2) ；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
Figure 2 shows the optical image of graphene domains with circular shape， indicating that the size of the domains is larger than 0.3 mm. The Raman spectrum of the graphene sample is shown in Fig. 3. As is shown in Fig. 3， 2D band and G band can be clearly identified. The intensity ratio of 2D band and G band is about 2， indicating that the sample is monolayer. D band cannot be found， suggesting the high quality of graphene. The SAED and LEED patterns also demonstrate the single crystalline nature of the graphene sample.
Experiment 2： Disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the steps of the growth comprise：
(1) The Cu foils without any pre-treatment are placed on quarts and then loaded into the chemical vapour deposition (CVD) system；
(2) The Cu foils are heated to 1000 ℃ in 60 min under an inert atmosphere， such as Ar with a flow rate of 500 sccm. Then the annealing process starts with 5 sccm H2 and lasts for 40 min；
(3) After the annealing process， the CH4 (5 sccm) is introduced as carbon source and the growth process lasts for 2 min. The H2 flow is not changed；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
The graphene synthesized therein has large domain size of about 0.3 mm and high quality.
Experiment 3： Disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the steps of the growth comprise：
(1) The Cu foils without any pre-treatment are placed on fused silica and then loaded into the chemical vapour deposition (CVD) system；
(2) The Cu foils are heated to 1000 ℃ under an inert atmosphere， such as Ar with a flow rate of 700 sccm， in 60 min. Then the annealing process starts with 5 sccm H2 and lasts for 40 min；
(3) After the annealing process， the CH4 (5 sccm) is introduced as carbon source and the growth process lasts for 2 min. The H2 flow is not changed；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
The graphene synthesized therein has large domain size of about 0.2 mm and high quality.
Experiment 4： Disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the steps of the growth comprise：
(1) The Pt foils without any pre-treatment are placed on Al2O3 and then loaded into the chemical vapour deposition (CVD) system；
(2) The Pt foils are heated to 1000 ℃ under an inert atmosphere， such as Ar with a flow rate of 500 sccm， in 60 min. Then the annealing process starts with 5 sccm H2 and lasts for 40 min；
(3) After the annealing process， the CH4 (5 sccm) is introduced as carbon source and the growth process lasts for 2 min. The H2 flow is not changed；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system. .
The graphene synthesized therein has large domain size of about 0.3 mm and high quality.
Experiment 5： Disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the steps of the growth comprise：
(1) The Pt foils without any pre-treatment are placed on quarts and then loaded into the chemical vapour deposition (CVD) system；
(2) The Pt foils are heated to 1000 ℃ under an inert atmosphere， such as Ar with a flow rate of 500 sccm， in 60 min. Then the annealing process starts with 5 sccm H2 and lasts for 40 min；
(3) After the annealing process， the CH4 (5 sccm) is introduced as carbon source and the growth process lasts for 2 min. The H2 flow is not changed；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
The graphene synthesized therein has large domain size (0.3 mm) and high quality.
Experiment 6： Disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the steps of the growth comprise：
(1) The Pt foils without any pre-treatment are placed on fused silica and then loaded into the chemical vapour deposition (CVD) system；
(2) The Pt foils are heated to 1000℃ under an inert atmosphere， such as Ar with a flow rate of 500 sccm， in 60 min. Then the annealing process starts with 5 sccm H2 and lasts for 40 min；
(3) After the annealing process， the CH4 (5 sccm) is introduced as carbon source and the growth process lasts for 2 min. The H2 flow is not changed；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
The graphene synthesized therein has large domain size of about 0.3 mm and high quality.
Experiment 7： Disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the steps of the growth comprise：
(1) The Au foils without any pre-treatment are placed on Al2O3 and then loaded into the chemical vapour deposition (CVD) system；
(2) The Au foils are heated to 1000℃ under an inert atmosphere (Ar flow is 500 sccm) in 60 min. Then the annealing process starts with 5 sccm H2 and lasts for 40 min；
(3) After the annealing process， the CH4 (5 sccm) is introduced as carbon source and the growth process lasts for 2 min. Tine H2 flow is not changed；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
The graphene synthesized therein has large domain size of about 0.3 mm and high quality.
Experiment 8： Disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the steps of the growth comprise：
(1) The Au foils without any pre-treatment are placed on quarts and then loaded into the chemical vapour deposition (CVD) system；
(2) The Au foils are heated to 1000℃ under an inert atmosphere (Ar flow is 500 sccm) in 60 min. Then the annealing process starts with 5 sccm H2 and lasts for 40 min；
(3) After the annealing process， the CH4 (5 sccm) is introduced as carbon source and the growth
process lasts for 2 min. The H2 flow is not changed；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
The graphene synthesized therein has large domain size of about 0.3 mm and high quality.
Experiment 9： Disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the steps of the growth comprise：
(1) The Au foils without any pre-treatment are placed on fused silica and then loaded into the chemical vapour deposition (CVD) system；
(2) The Au foils are heated to 1000 ℃ under an inert atmosphere (Ar flow is 500 sccm) in 60 min. Then the annealing process starts with 5 sccm H2 and lasts for 40 min；
(3) After the annealing process， the CH4 (5 sccm) is introduced as carbon source and the growth process lasts for 2 min. The H2 flow is not changed；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
The graphene synthesized therein has large domain size of about 0.3 mm and high quality.
All these above experiments demonstrate that rapid growth of large single-crystal graphene samples can be realized assisted by oxide substrates.
Second embodiment
Following experiments are carried out to check the role of CH4 flow and the growth time in this rapid growth of large single-crystal graphene assisted by oxide substrate.
Experiment 1： Disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the steps of growth comprise：
(1) The Cu foils without any pre-treatment are placed on Al2O3 and then loaded into the chemical vapour deposition (CVD) system；
(2) The Cu foils are heated to 1000 ℃ under an inert atmosphere (Ar flow is 300 sccm) in 60 min. Then the annealing process started with 5 sccm H2 and lasts for 40 min；
(3) After the annealing process， the CH4 (0.5 sccm) is introduced as carbon source and the growth process lasts for 20 min. The H2 flow is not changed；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
The graphene synthesized is circular and has large domain size (0.7 mm) and high quality.
Experiment 2： Disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the steps of growth comprise：
(1) The Cu foils without any pre-treatment are placed on Al2O3 and then loaded into the chemical vapour deposition (CVD) system；
(2) The Cu foils are heated to 1000 ℃ under an inert atmosphere (Ar flow is 300 sccm) in 60 min. Then the annealing process starts with 5 sccm H2 and lasts for 40 min；
(3) After the annealing process， the CH4 (0.2 sccm) is introduced as carbon source and the growth process lasts for 60 min. The H2 flow is not changed；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
The graphene synthesized is hexagonal and has large domain size (0.7 mm) and high quality.
These experiments demonstrate that the growth time should be extended when CH4 flow decreases to obtain same size graphene domains. The CH4 flow also affects the shape of graphene domains. When the CH4 flow is large， the shape is circular； When the CH4 flow is small， the shape is hexagonal.
Third embodiment
Following experiment is carried out to check the role of H2 flow in this rapid growth of large single-crystal graphene assisted by oxide substrate.
Experiment 1： Disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the steps of growth comprise：
(1) The Cu foils without any pre-treatment are placed on Al2O3 and then loaded into the chemical vapour deposition (CVD) system；
(2) The Cu foils are heated to 1000 ℃ under an inert atmosphere (Ar flow is 300 sccm) in 60 min. Then the annealing process starts with 5 sccm H2 and lasts for 40 min；
(3) The CH4 (5 sccm) is introduced as carbon source and the growth process lasted for 2 min. The H2 flow is changed to 50 sccm；
(4) After the growth process， the power is turned off and the system is naturally cooled to room
temperature with Ar and H2 flowing in the CVD system.
The graphene synthesized has small domain size (0.1 mm) with hexagonal shape.
Comparing with Experiment 1 of First embodiment， this experiment shows that when the H2 flow in growth process is high， the shape of domains will change to hexagonal and the size gets smaller.
To compare with above experiments， following comparing experiment is carried out to check the growth mechanism of large single-crystal graphene assisted by oxide substrate.
Comparing experiment 1： Disclosed is a method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the steps of growth comprising：
(1) The Cu foils without any pre-treatment are placed on graphite and then loaded into the chemical vapour deposition (CVD) system；
(2) The Cu foils are heated to 1000 ℃ under an inert atmosphere (Ar flow is 300 sccm) in 60 min. Then the annealing process started with 5 sccm H2 flow in 40 min；
(3) After the annealing process， the CH4 (5 sccm) is introduced as carbon source and the growth process lasts for 2 min. The H2 flow is not changed；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
The graphene synthesized has small domain size (15 μm) with hexagonal shape as shown in Fig. 5.
This experiment shows that the O released from oxide substrate at high temperature is the key factor in the rapid growth. The metal foil adheres to the oxide substrate with very narrow space at high temperature. The O released from the oxide could diffuse to the metal surface and involve in the catalytic reaction. This would drastically lower the barrier of the feedstock decomposition and increase the carbon species supply by orders of magnitude， which enables the rapid growth ofgraphene. Also， the active sites for nucleation could be killed by O， resulting in the decrease of the nucleation density.
Fourth embodiment
Continuous rapid growth of large single-crystal graphene assisted by oxide substrate can be realized by the apparatus shown in Fig. 6. As shown in Fig. 6， major portion of the Cu foil is wound around a first roller on the left of the apparatus， such as a CVD system， with one end of the Cu foil wound around a second roller on the right of the apparatus. Between the first roller and the second roller lies a heating zone with an appropriate temperature for growth of single crystal graphene. An oxide substrate is placed in the heating zone， right below Cu foil. When
the process of growth begins， the second roller can rotate about its axis perpendicular to the plane of the paper， and the Cu foil can be transferred from the first roller to the second roller. During the transfer of the Cu foil through the heating zone， single crystal grapheme can be achieved on the surface of the Cu foil.
With the help of the apparatus shown in Fig. 6， carried out is a method for continuous rapid growth of large single-crystal graphene assisted by oxide substrate， wherein the steps of growth comprise：
(1) The Cu foils without any pre-treatment are placed on Al2O3 and then loaded into the chemical vapour deposition (CVD) system. The two ends of the Cu foil are fixed on the rollers at the inlet and the outlet of the tube furnace；
(2) The Cu foils are heated to 1000 ℃ under an inert atmosphere (Ar ＝ 300 sccm) in 60 min. Then the annealing process starts with 5 sccm H2 flow and lasts for 40 min；
(3) After the annealing process， the CH4 (0.5 sccm) is introduced as carbon source and the growth process lasts for 20 min. The Cu foil continuously goes through the heating zone of the CVD system assisted by the roller. The H2 flow is not changed；
(4) After the growth process， the power is turned off and the system is naturally cooled to room temperature with Ar and H2 flowing in the CVD system.
High quality graphene film with large single-crystal domains is synthesized continuously.
Claims (15)
- A method for rapid growth of large single-crystal graphene assisted by oxide substrate， wherein metal foils are placed on oxide substrates and large single-crystal graphene domains are grown on the back side of metal foils facing the oxide substrates.
- The method of claim 1， wherein the metal foils are the commercial ones without any pre-treatment.
- The method of claim 1， comprising：(1) the metal foils are placed on oxide substrates and then loaded into a chemical vapour deposition (CVD) system；(2) the system is heated to 900～1100℃ under an inert atmosphere and then an annealing process starts with 0.2～500 sccm H2 flow；(3) after the annealing process， CH4 with a flow rate of 0.5～50 sccm is introduced as a carbon source and a growth process begins and lasts for 1s～60min；(4) after the growth process， the power of the chemical vapour deposition (CVD) system is turned off and the system is naturally cooled to room temperature.
- The method of claim 1， comprising：(1) the metal foils without any pre-treatment are placed on oxide substrates and then loaded into a chemical vapour deposition (CVD) system；(2) the metal foils are heated to 900～1100℃ in 50～70 min under an inert atmosphere of Ar flow of＞300 sccm and then an annealing process starts with 2～50 sccm H2 flow and lasts for 30～100min；(3) after the annealing process， CH4 gas with a flow rate of 0.5～50 sccm is introduced as a carbon source for the graphene growth and a growth process begins and lasts for 1s～60min， meanwhile the H2 flow is tuned to 0.2～50 sccm；(4) after the growth process， the power of the system is turned off and the system is naturally cooled to room temperature with Ar and H2 flow therein.
- The method of any preceding claim， wherein the oxide substrates are made of at least one of the following materials： quartz， fused silica， mica， Al2O3， CaO， ZrO， MgO ， Cr2O3 and other high temperature oxides.
- The method of claim any preceding claim， wherein the metal foils are made of at least one of the following materials： copper (Cu) ， platinum (Pt) and gold (Au) .
- The method of claim 3 or claim 4， wherein H2 is not introduced into the system during the heating process.
- The method of claim 3 or claim 4， wherein the system is under atmospheric pressure during the heating， annealing， growth and cooling processes.
- The method of claim 3 or claim 4， wherein the flow of CH4 is 0.5～50 sccm and the flow of H2 is 0.2～50 sccm in step (3) with a ratio of the CH4 flow to the H2 flow 0.01～100.
- The method of claim 3 or claim 4， wherein in step (3) the metal foils adhere to the adjacent oxide substrates with very narrow spaces at high temperature so that O released from the oxide could diffuse to the metal surface and involve in the catalytic reaction， resulting in drastically lowering the barrier of the feedstock decomposition and increasing the carbon species supply by orders of magnitude， which enables the rapid growth of graphene； meanwhile the active sites for nucleation could be killed by O， resulting in the decrease of the nucleation density.
- The method of any preceding claim， wherein the shape of the single graphene domains is circular or hexagonal with a diameter of＞0.2mm.
- The method of any preceding claim， wherein the metal foils are placed on the oxide substrates dynamically and the metal foils are transferred from a first roller to a second roller with the metal foils passing through a heating zone to grow single graphene domains continuously on the metal foils.
- A kind of large single-crystal graphene， wherein the growth of the graphene is carried out with any method of claims 1-12， and the shape of the single graphene domains is circular or hexagonal with their diameters of＞0.2mm.
- An equipment for rapid and continuous growth of large single-crystal graphene assisted by oxide substrate， comprising：a first roller with major portion of a metal foil wound around it and a second roller for connecting one end of the metal foil installed in a growth system before a growth process， between which lies a heating zone with an appropriate temperature for the growth of the single crystal graphene； andoxide substrates placed in the heating zone， right below metal foils.
- The equipment of claim 14， wherein more than one metal foil is placed on more than one oxide substrate with metal foils and oxide substrates stacked alternately and the number of the first rollers， the number of the second rollers and the number of the metal foils are equal.
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| CN201610191702.1 | 2016-03-30 | ||
| CN201610191702.1A CN105624778B (en) | 2016-03-30 | 2016-03-30 | A kind of quick method for continuously preparing big domain graphene film |
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