Hand rubbing nuclear fusion live in the wilderness

Chapter 405 The Sigh of Huaguo Experts

Carbon-based chips and biological chips are very different in nature. Although the human body is not very resistant to carbon-based chips, it does not mean that the human body can implant carbon-based chips without any sequelae.

In fact, when he got the 'carbon-based integrated circuit board preparation information' a long time ago, Han Yuan thought about using this technology to benefit those with disabilities or people with physical defects.

But after careful consideration, he finally gave up on the idea.

Without him, this technology will be exploited by some people with ulterior motives.

Take a very simple example.

When you were walking on the street one day, you were knocked unconscious by a brick, and then a chip was implanted. Since then, you have been controlled for the rest of your life.

Even your memory is artificially synthesized false memory.

For example, you worked 12 hours, but the boss implanted the memory that you had already rested for 12 hours.

This kind of thing is scary when you think about it.

In the chemistry laboratory, Han Yuan did not respond to the audience's inquiries in the live broadcast room, but changed the topic.

The shooting device faces the prepared equipment and materials on the experimental table, and records them one by one in the live broadcast room.

The audience can clearly see the label on each material and the name of the corresponding equipment.

Graphite, silicon carbide, methane, high temperature smelting furnace,.
Taking a picture of the prepared equipment, Han Yuan said: "These materials and equipment on the table are needed for smelting graphene this time."

"In addition, there is a single crystal furnace that is not here because the equipment is too large. Everyone can see it when it is in use."

"I won't say much about the use of graphene. In addition to being used as a substrate material for carbon-based chips, there are various other uses."

"This time to synthesize graphene materials, I mainly talk about the methods used and the details that need to be paid attention to during the manufacturing process."

After a pause, Han Yuan reached out to pick up the glass bottle containing graphite from the table, took a piece from the middle with tweezers, and said:
"This one in my hand is the main raw material 'graphite' for making graphene"

"Everyone knows that there are many allotropes of carbon, and graphene and graphite are two of them."

"These two materials, besides the fact that they are both allotropes of carbon, are closely related."

"To be precise, graphene is an atomic layer of graphite. It is a layer of sp2-bonded carbon atoms arranged in a hexagonal or honeycomb lattice material, which is the main component of graphite."

"The preparation of graphene is actually quite simple."

"At the beginning of the 21st century, two scientists in the country where the sun never sets discovered that they could obtain thinner and thinner graphite flakes in a very simple way."

"They exfoliated graphite flakes from graphite using a special adhesive tape."

"Then glue both sides of the sheet to a special type of adhesive tape, and tear off the tape to split the graphite sheet in two."

"Continuously using the tape to tear the graphite film like this, the thin film sticking to the tape will become thinner and thinner. Finally, they got a thin film composed of only one layer of carbon atoms, which is graphene."

"It's just that the graphene obtained in this way is not very useful because it sticks to the tape and cannot be removed, and the single layer of graphene is too fragile and incomplete."

"Although the graphene layers produced by the two scientists were unusable, this sparked interest in graphene."

"Since then, graphene preparation methods have emerged in an endless stream, such as micro-mechanical exfoliation, chemical vapor deposition, oxidation-reduction, solvent exfoliation, high-temperature reduction, light reduction, etc."

"These methods of making graphene each have their own advantages and disadvantages."

"For example, the micromechanical exfoliation method has the advantage that it can produce high-quality graphene, but its disadvantages are low yield and high cost, which cannot meet the requirements of industrial and large-scale production, so it can only be used as a small-scale preparation in the laboratory. .”

"And what I use to prepare graphene today is a method that combines the advantages of chemical vapor deposition and crystal nucleus epitaxy."

"It's called 'vapor deposition-nuclear crystallization smelting method'."

"This method can produce high-quality, large-area graphene."

"And the combination of the two avoids their respective shortcomings."

"For example, graphene prepared by crystal nucleus epitaxy has the characteristics of high quality and high carrier mobility, but it cannot observe the quantum Hall effect."

"As for the quantum Hall effect, to put it simply, if there is this effect, the energy consumption of transistors and electronic devices will be reduced a lot."

"The low energy consumption of carbon-based chips is partly due to the quantum Hall effect. Its existence will cause the magnetic field to generate a lateral force on the electrons in the conductor, thereby generating a voltage difference at both ends of the conductor, effectively increasing the transport of electrons."

"The graphene prepared by 'vapor deposition-nuclear crystallization smelting method' makes up for the shortcomings of the crystal nucleus epitaxy method, and is more suitable for preparing the bottom material of carbon-based chips."

"Okay, I don't need to say anything superfluous. I will explain the rest of the introduction during the preparation process."

Saying that, Han Yuan put the graphite back into the glass bottle, and brought these materials and equipment to another room of the chemical laboratory, where there is a single crystal furnace.

'Vapor deposition method' is a method in smelting materials, the main classification is under chemical smelting, this is also the method he uses the most and is most familiar with.

As for the extra crystal nucleus crystallization step, as long as the material for crystallization is selected, it is not too difficult.

If there is a disadvantage to this method of smelting graphene, it should be that the smelting equipment used in the smelting process is more expensive.

Whether it is a high-temperature smelting furnace or a single crystal furnace, the value of one is several million or even tens of millions.

However, the 'vapour phase deposition - crystal nucleus extension smelting method' has another great advantage.

That is, this method can realize intelligent control, that is, after setting various conditions such as smelting temperature, smelting time, and access to crystal nuclei, it can be controlled through artificial intelligence programs.

Most of the whole process can be realized unattended.

South Korean won will not toss out a very complicated method of graphene smelting, because it is not worth it, neither for him nor for the countries in reality.

After all, in reality, there is no way to mass-produce graphene in the hands of various countries.

For example, the single crystal extension epitaxy method (one of the crystal nucleus extension methods) developed by Chinese American professor Yu Qingkai of Texas State University and Chen Yong, an assistant professor of Purdue University, can produce graphene in batches.

However, it also has the disadvantages of high cost and thick graphene layer.

The mass production technology of graphene is not a black technology, and all countries have researched and mastered it.

It's just that it is difficult to produce large-area, high-quality graphene without grain boundaries.

In the laboratory, Won handles graphite, silicon carbide and other materials in his hands.

Although the preparation of graphene by 'vapour phase deposition-crystal nucleus extension smelting method' has high requirements on equipment, the requirements on the environment are not very high.

The rooms in the relocated chemical laboratory are all Class [-] dust-free laboratories, which can fully meet the needs.

So the won can be processed directly in the chemical laboratory.

Graphite and silicon carbide are used to remove visible impurities, remove surface oxide layer and corrosion layer caused by long-term storage, and then soak in a special solution for 5 minutes, then wash again.

Taking advantage of the time when processing graphite and silicon carbide materials, South Korea assembled the equipment for preparing graphene as a whole.

The equipment needed is not much, a high-temperature smelting furnace and a single crystal furnace, just these two equipments.

The two devices are connected together, and the elemental carbon and high-purity graphite powder smelted in the single crystal furnace can be directly sent to the high-temperature smelting furnace through the conveyor belt.

Before the graphene is smelted, it is closed as a whole, and during the smelting process, it will be further purified by injecting methane, ethylene and other gases, so the requirements for the external environment are not high, and there is no need for a top-level dust-free studio.

Smelting materials by chemical vapor deposition is an all-too-familiar step for Won.

The cleaned graphite and silicon carbide are put into the single crystal furnace.

Won adjusted the parameters and started the smelting equipment.

The temperature in the single crystal furnace rose rapidly under the support of high-frequency, high-voltage current, and reached [-] degrees in a few minutes.

At this temperature, both graphite and silicon carbide materials will be vaporized.

After the equipment was turned on, Won stood aside and waited for the vaporization to complete. By the way, I would like to explain the points that need to be paid attention to in the process of preparing graphene:

"There are a few caveats in the preparation of graphene."

"Such as single crystal smelting furnace equipment, its function is to gasify graphite, further purify it, and turn it into elemental carbon or high-purity graphite powder."

"Here, the single crystal furnace needs to be vacuumed, and the temperature needs to be raised to more than [-] degrees to vaporize the graphite, thereby forming higher-purity carbon powder or graphite powder."

"The role of the high-temperature smelting furnace is to re-gasify the purified graphite powder and elemental carbon, and then re-grow hierarchically on the single crystal nucleus on the chassis, so that high-quality graphene blocks can be obtained."

Hearing this, some keen viewers in the live broadcast room immediately raised their doubts.

[If you want to use high-purity carbon powder or graphite powder, can't you just add graphite?Why add silicon carbide into it? 】

Some viewers in the live broadcast room raised their own questions, causing other viewers to think about it and ask questions along the way.

Seeing the barrage, Han Yuan smiled and said, "If you want to simply prepare high-purity graphite powder, of course you only need to add graphite."

"But my ultimate goal is to produce graphene, and in this process, silicon carbide acts as a crystal nucleus in the production process of graphene."

"At a high temperature of more than [-] degrees, silicon carbide will also be vaporized into extremely fine particles."

"These particles are mixed in graphite powder and carbon powder. In the high-temperature smelting furnace, they will be used as the core nuclei to generate graphene blocks without grain boundaries, which can further improve the quality of graphene."

"And silicon carbide is a semiconductor material, and a small amount of doping in the bottom layer of graphene will not affect the quality of the final chip."

The corresponding explanation was spoken, and words such as "So it is so", "That's how it is", and "Understood" were suddenly filled on the barrage.

But in fact, most of the viewers in the live broadcast room only understood part of it, that is, the quality of graphene can be improved.

As for why, these people are not clear.

On the contrary, the scientists from all over the world who were squatting in the live broadcast room were immediately enlightened after hearing Han Yuan's explanation, and the thoughts in their minds were instantly opened.

Especially Huaguo's graphene-related experts stared at the live broadcast without blinking.

Except for a very small number of materials in this world, such as single crystal silicon, most of the materials have grain boundaries.

The existence of grain boundaries has advantages and disadvantages for materials.

Its existence can sometimes increase the toughness of the material, lower the melting point of the material, and so on.

But in a chip, grain boundaries are not a good thing because they degrade the performance of the chip.

This is why the manufacture of silicon-based chips requires people to spend a lot of effort to build a single crystal furnace and prepare single crystal silicon.

It is because there is no grain boundary in monocrystalline silicon as a whole, which can improve the performance of the chip.

The same is true for graphene materials.

If graphene is to be used to make carbon-based chips, the grain boundaries in the graphene layers are the first problem.

On this issue, Huaguo has actually found a corresponding solution.

The solution is actually somewhat similar to the one used by the Korean won.

They removed Si by heating single crystal 6H-SiC (hexagonal silicon carbide) by heating silicon carbide, and then decomposed graphene sheets on the single crystal carbon surface.

The specific manufacturing method is to heat the sample obtained by etching with oxygen or hydrogen under high vacuum by electron bombardment to remove oxides.

Then use Auger electron spectroscopy to confirm that the oxide on the surface is completely removed, heat the sample to 1250~1450°C and keep it for 10 minutes to form a very thin graphite layer, and finally peel it off by micromechanics method to obtain a graphene layer.

The resulting graphene layers are of high quality, without grain boundaries, and can be used to make carbon-based chips.

But this method cannot be mass-produced, and the high-purity hexagonal silicon carbide single crystal also mainly relies on imports.

This largely limits the development of carbon-based chips.

The experts in Huaguo have been trying to solve this problem, but so far there has been no much progress.

It never occurred to them that silicon carbide could still be used in this way, and the truth is only one step away from what they can say.

Wanting to understand these words, the expert squatting in front of the screen looked at the figure in the live broadcast room and sighed.

From this incident, they once again saw the gap between themselves and the other party, as well as the gap in technology and the cognition of the properties of certain materials between the two sides.

Sometimes they may be only one step away from the end, but often this step is blocked by a lot of debris.

They wasted a lot of time in the process of removing these sundries, but the other party directly burned the sundries and garbage directly.

Although this metaphor is somewhat inappropriate, it can be said to be very vivid.

(End of this chapter)