Chapter 256 Experiment is successful, technology is world-leading [Subscription required]

"I'm glad to have you here, Academician Xu. Seeing that the project has not made any progress, I want to change to a new radar research direction."

At the 14th Research Institute in Jinling, Zhang Guangyi was very excited to see Xu Yuan.

After saying this, I forgot to let go of the hand I was holding.

The core module of the ground radar still has unresolved problems due to gallium nitride material technology, which makes it impossible for gallium nitride radar to be equipped and put into service. This has become his biggest worry.

For this reason, he has considered using other means to improve the performance of the radar during this period of time.

But for now, using gallium nitride materials to make radar devices is the best solution.

Although he really hoped that Xu Yuan could come to Jinling as soon as possible to help optimize gallium nitride technology.

But there is nothing we can do since the other party is busy with mathematics.

Just be patient.

Fortunately, the Lantern Festival had just ended, and Xu Yuan had returned to their 14th Institute. According to the previous progress, it was believed that it would not take too long.

On this point, Zhang Guangyi has full confidence in Xu Yuan.

Otherwise, he wouldn't be so excited when seeing Xu Yuan today.

Even go to the station to pick people up in person.

After Xu Yuan finished dealing with family affairs, he returned to Yanjing after the Chinese New Year. The first project he worked on in the new year was the research on gallium nitride technology.

I saw that after the award ceremony at the Journal of Mathematics, work was back on track.

After saying hello to Academician Zhang Guangyi, he returned to Jinling again.

At this moment in Zhang Guangyi's office at the research institute, Xu Yuan smiled and replied after hearing what the other party said:
"Academician Zhang, you are too serious. I also want to see our aircraft equipped with gallium nitride radars."

Just as the two were greeting each other, a slightly surprised voice suddenly came from outside the office.

"Old Zhang."

"I heard that Academician Xu is here. Where is he?"

Because the door of Zhang Guangyi's office was open, the two of them subconsciously turned their heads to look when they heard the words.

The next second Xu Yuan saw a middle-aged man with a Mediterranean hairstyle rushing into his field of vision.

He also wore a pair of narrow-framed glasses on his face.

Xu Yuan was sure that he did not know the person in front of him, but judging from the fact that the other party called him Zhang Guangyi, he thought that they should be quite familiar with each other.

Then he turned his gaze to Zhang Guangyi beside him, waiting for him to introduce himself.

At this time, Zhang Guangyi noticed the visitor and immediately smiled and hurriedly introduced them to each other.

"Xu Yuan, let me introduce you. This is Professor Liu Wensen, the vice president of the School of Electronic Science and Engineering of Jinling University and a specially appointed expert."

"I have been engaged in the research of gallium nitride-based semiconductor material growth for a long time and have rich experience in this area."

Zhang Guangyi was standing between the two of them. After introducing Xu Yuan, he said to Liu Wensen next to him:
"Vincent, you came at the right time. This is the newly elected academician of the two academies, our most talented scientist."

"You should know Xu Yuan, right?"

"In the scientific community, there should be no one who is not familiar with the name Xu Yuan." Liu Wenshen responded with a smile.

As soon as he finished speaking, he continued, "But today is the first time I have met Academician Xu face to face."

"Professor Liu has been researching the growth technology of gallium nitride materials. I wonder if there are any new developments." Xu Yuan's attention was all on gallium nitride. He grasped the key point and asked subconsciously.

It can be seen that Zhang Guangyi and Liu Wenshen have a good relationship. In addition, Liu Wenshen's research field is gallium nitride technology, so it seems that he must have carried out many related experiments during this period.

He understood this very well.

Previously, he was worried about the first Xu Yuan Mathematics Award and was unable to carry out gallium nitride technology experiments in a timely manner.

Solve the problem of GaN substrate materials.

Under such circumstances, the 14th Institute would definitely not stop the project.

It is completely normal to invite Professor Liu Wenshen from Jinling University to participate in the research.

Xu Yuan hoped that Liu Wenshen had made a breakthrough in the research of substrate materials.

At least this can save you a lot of time.

You have to know that the development of science and technology cannot be achieved by him alone. It is impossible for him to develop and apply all the advanced technologies in all fields.

Therefore, it is a happy thing for everyone that outstanding scientific researchers emerge.

That is why he is concerned about Liu Wenshen's progress.

At this moment, when Liu Wenshen heard Xu Yuan's question, the expression on his face suddenly became unnatural, and a hint of embarrassment appeared.

After a brief pause, he explained his research progress truthfully without leaving any doubts on the matter.

"I'm not afraid of you laughing at me, but up to now, we are still facing two core challenges in GaN substrate materials. Although we have conducted many experiments on these two problems, unfortunately the final experimental results are still unsatisfactory."

"On the selection of substrate materials, our views are very similar to yours, Academician Xu."

“That’s choosing silicon.”

"First, silicon is the second most abundant element in the earth's crust and has excellent physical and chemical properties."

"The overall cost of making gallium nitride devices on large-size silicon substrates can be reduced by about 30 percent."

When it came to his professional field, Liu Wenshen did not stop and continued to explain the details.

"But the problem we are facing now is that the thermal expansion coefficients of silicon and gallium nitride differ by more than 50%. When cooling to room temperature, the gallium nitride film will be subjected to huge tensile stress, causing cracks, which cannot meet the requirements for device manufacturing."

"Furthermore, the lattice mismatch between GaN and silicon is nearly 20 percent, which will produce high-density dislocations in the epitaxial film."

“This causes the crystal quality to deteriorate, and it is impossible to obtain high-quality devices.”

When he spoke the last part, Liu Wenshen did not hide the regret in his eyes at all.

As a long-term research project of my own, I know the problems I face, but I don’t have a good way to solve them.

One can imagine how he felt.

It is inevitable that there will be a sense of powerlessness and regret.

For him, naturally, he hopes to see these two core issues resolved as soon as possible.

So when he learned that Xu Yuan had come to the 14th Institute, he couldn't wait to rush over from school.

To be honest, in his opinion, Xu Yuan is best at proving conjectures in the field of mathematics. Moreover, relying on engineering expertise such as fluid mechanics, he has also made outstanding contributions in the fields of aviation and aerospace.

However, the field of materials is so cross-disciplinary that it is hard not to feel a little worried.

Although Xu Yuan participated in and completed high-performance carbon fiber composite materials, there are still some differences from semiconductor materials.

As for the new lithium iron phosphate battery technology, it relies on a brand-new battery structure design.

Different from specific material research.

Under such circumstances, it was difficult for him to be sure that Xu Yuan could really solve these two core technical problems.

However, because Zhang Guangyi has great trust in Xu Yuan, and they currently have no good solution, they can only place their hopes on Xu Yuan.

Xu Yuan didn't know what Liu Wenshen was thinking at the moment. After hearing these words, he nodded in agreement.

"The large difference in expansion coefficient and lattice mismatch are indeed technical challenges that must be solved, but as far as the current situation is concerned, silicon is still a more suitable substrate material."

"Who says it isn't?"

Liu Wenshen agreed, “In fact, we have also conducted relevant research and tried to use other materials to replace the substrate, but the results were even less ideal.” His words were full of regret.

"There are definitely technical difficulties, but I believe they can be solved."

"I like the confidence of young people. I feel more at ease with your words." Zhang Guangyi took over Xu Yuan's words and agreed with a smile.

As long as the gallium nitride material technology is solved, he can immediately research gallium nitride radar.

Perform comprehensive testing of GaN radar.

By then, domestic radar modules will be replaced as soon as possible and all will use gallium nitride radars.

By that time, even the stealth strategic bomber known as the Ghost could be detected at a long distance.

He is very much looking forward to the arrival of this day.

The next second, Liu Wenshen did not remain silent and immediately made a request to Xu Yuan.

"Academician Xu."

"Shall we serve as your assistants and participate in the experiment?"

"It's my honor to have a great professor as my assistant. Maybe we can achieve results soon." Xu Yuan smiled and warmly welcomed Liu Wensheng's request.

Just as he said just now, with the help of senior professors like Liu Wenshen, R&D efficiency will definitely be twice as good with half the effort.

After all, relying on the panel can greatly reduce the cost of trial and error, and it will be more efficient with Liu Wenshen's help.

After hearing Xu Yuan's answer, Liu Wenshen finally felt relieved and was full of anticipation for the subsequent experiments.

Then Zhang Guangyi thought of something else and gave another special instruction.

“It is a good thing that the problems facing GaN technology can be solved as soon as possible, but you must not feel pressured, as there is still a long time this year.”

Xu Yuan listened to everything Zhang Guangyi said and naturally knew that the other party was considering him.

This will avoid carrying too much pressure on your shoulders, which will eventually lead to a bottleneck in the progress of the experiment.

But for Xu Yuan, this kind of thing basically does not exist.

When it comes to proving the world's most difficult mathematical problems, you may run into bottlenecks and often need inspiration. But as far as materials are concerned, as long as you do more experiments, you can always find a solution by relying on the panel.

Therefore, in order to reassure Academician Zhang Guangyi, he thought about it and responded to the other party.

"Academician Zhang, please relax. The research time for GaN substrate material technology will definitely not be too long."

"My expected goal is to see progress within two months."

He was not talking nonsense. You should know that he had conducted experiments before.

In addition, a large amount of relevant literature has been collected during this period, and with the help of Liu Wenshen this time, it is normal to achieve breakthrough progress within two months.

More importantly, two months from now, it will be a day that everyone is looking forward to.

Tiangong, a completely independently designed and built space station belonging to China, welcomed the launch and docking of the final experimental module.

By then, it will also mark the completion of the Tiangong Space Station. From the decision to build our own space station to its full completion and use, it took only a few years.

Looking at the entire aerospace field in the world, it can be called a great aerospace miracle.

You have to know that the International Space Station, which is currently in service, had so many members participating in its construction, and it took a full ten years to complete.

One can imagine what kind of wave it would create in the world when the news of the completion of the Tiangong docking is announced.

As a staff member of the Space Technology Research Institute, he also participated in part of the construction of the space station. He will definitely go to the launch site of the final experimental module and witness the arrival of this great aerospace miracle with his own eyes.

This matter was specifically reminded to him by Chen Jianfang when he returned to Yanjing from his hometown and went to Chen Jianfang's home to pay New Year's greetings.

So it is definitely not possible to be absent.

Liu Wenshen's main research topic every day is the problems encountered with gallium nitride substrate materials, and he is not very clear about things in the aerospace field.

He only heard Xu Yuan say that it would take two months to make a breakthrough in substrate material research.

This is quite surprising.

Only by personally participating in relevant research can one truly realize the difficulty of solving the problems of excessive expansion and lattice mismatch.

It is absolutely unimaginable that it would take only two months.

Otherwise, they would not be still helpless about these two problems after studying them for so long.

There is no way to reach the expected value.

Although it is indeed a good thing to be confident in project research and not to deny yourself easily.

Blind self-confidence is also undesirable.

Otherwise, once you fall into your own misunderstanding, you don’t know how much time will be wasted.

So his thought stayed here, and after a slight hesitation he took the initiative to express the doubts in his heart.

"Does Academician Xu have a solution to these two problems with silicon substrate materials? That's why he is confident that he can make progress so quickly?"

Yes.

In his opinion, Xu Yuan said this because he must have found a solution and was confident about it.

After all, as long as you determine the correct research direction and follow the steps, you will definitely reach the end.

This is much better than trying randomly at a complex and confusing intersection.

But unfortunately he didn't guess right this time.

Xu Yuan also knew that it would be difficult for others to believe what he said, but what did it matter?

Anyway, when the experimental results come out, we will know the situation.

So he didn't intend to keep it a secret, and started explaining directly after hearing Liu Wenshen's words.

"I haven't thought of a specific solution yet, but the process will definitely not be slow."

"Is that so?" Liu Wensen sounded a little worried when he heard that.

Zhang Guangyi, who was standing next to him, saw this scene and took the initiative to change the topic.

"Let's not talk about this for now. It just so happens that both of you are here today. I'll pay for your dinner tonight."

"Just consider it as an early celebration for you."

He still had a smile on his face while speaking, and did not question what Xu Yuan said at all.

He got to know Xu Yuan during the first flight test of the stealth unmanned bomber and discussed the active phased array radar. He knew Xu Yuan's character very well.

Since Xu Yuan could take the initiative to say something like this, it means he must be confident in his heart.

He was looking forward to hearing good news from Xu Yuan in two months.

After hearing Xu Yuan's answer, Liu Wenshen wanted to say something, but was interrupted by Zhang Guangyi, so he swallowed the words back.

Xu Yuancai is the chief project leader in this research project on gallium nitride substrate materials.

His identity is Xu Yuan's assistant, so in this situation he can only place his hopes on Xu Yuan.

……

Zhang Guangyi did not say anything nonsense. In the evening, he actually paid for Xu Yuan, Liu Wenshen, and several other members of the project to have dinner at a hotel in Jinling.

It is worth mentioning that no one mentioned work during the meeting, which made the atmosphere very harmonious.

It was not until the next morning that Xu Yuan and Liu Wensheng arrived at the laboratory on time.

After changing into the experimental protective clothing, we officially started the research work on gallium nitride silicon substrate materials.

As expected, the first few days were tough, and the new approach was quickly abandoned.

A waste of time.

However, this situation did not last long, and Xu Yuan's experiments subsequently progressed smoothly.

Liu Wenshen, who worked as an assistant, was also quite shocked by this change.

In just a few days, the research on GaN substrate material technology seemed to have suddenly found the right direction. Although the distance expansion and lattice mismatch problems have not been completely solved, the positive feedback brought by the daily progress makes people excited and more confident.

Even Liu Wenshen's threshold was greatly raised after experiencing several surprises.

Later on, my state of mind improved a lot.

Even if there is a small progress, we will remain calm.

In addition, he gradually believed what Xu Yuan had said before, and perhaps the experiment could be completed within two months.

Although he himself felt it was incredible before he saw it actually happen.

-

In the blink of an eye, it is April.

More than a month has passed since Xu Yuan and Liu Wenshen conducted experiments on gallium nitride substrate materials.

On this day in the laboratory, Xu Yuan and Liu Wensheng, wearing protective clothing, were still conducting material growth experiments.

"Academician Xu."

"Your way of dealing with this is really ingenious."

"I think the results of this experiment will not disappoint everyone. My intuition has always been very accurate."

When Liu Wenshen saw the technical methods used by Xu Yuan, he was simply astonished by how ingenious they were.

So much so that I couldn't help but praise it out loud.

The admiration for Xu Yuan in her eyes and the worry when they first met were completely different.

Xu Yuan stood beside the laboratory table, carefully placed the materials into the equipment, and proceeded to the next steps.

After finishing, he turned around and continued with a smile on his face:
"We will have to wait for the detailed material testing report to come out before we know the specific data."

Although he responded modestly on the surface, he did not feel the slightest bit of worry in his heart.

Because he had noticed during the experiment that the progress bar on the gallium nitride technology on the panel had reached 100%.

In other words, he successfully solved the problems of silicon substrate materials, such as differential expansion coefficient and lattice mismatch.

Of course, the specific performance of the final gallium nitride material device will definitely require more detailed testing.

Liu Wenshen could no longer control his emotions at this moment, and continued speaking excitedly.

"A stress buffer layer is added to the substrate during the growth process, and the film is in a compressive stress state during the cooling process. This method can avoid the occurrence of cracks."

"At the same time, we have also innovated the gallium nitride growth technology to obtain high-quality gallium nitride films."

Every word between the lines is a praise for the technology that Xu Yuan is researching, and it seems that he is in a state of great recognition.

"It is not realistic to force silicon substrate materials to avoid the problem of large expansion coefficient. After all, this is a characteristic of silicon itself. The only way to solve it is to add a stress buffer layer."

Xu Yuan took over Liu Wensheng's words and added two more sentences, explaining the solution in detail.

In addition to the stress buffer layer on the silicon substrate, his design also includes a current spreading layer, an electron cooling layer, an electron blocking layer, etc.

Only with so many structures as a safeguard can high-quality gallium nitride films be grown.

And ensure the yield rate.

In this way, the production cost of gallium nitride will naturally drop significantly.

You should know that in the past, when gallium nitride films were prepared through substrate materials, a large number of cracks would occur, which means that the yield rate was very low. So many gallium nitride films with cracks were discarded, which naturally increased the cost to a very high price.

After completing the relevant material procedures, all that was left for Xu Yuan and Liu Wenshen was to wait patiently.

A detailed inspection report is required to determine whether the project can be declared completed.

The laboratory at the 14th Institute has relatively advanced and complete equipment, so it does not take too long to wait for a detailed test report.

Not long after Liu Wenshen got it, he immediately lowered his eyes to look at the data above, and soon his body began to tremble slightly with excitement.

After taking a deep breath, he raised his eyes and said to Xu Yuan:
"We have successfully obtained high-quality GaN films, and all data are higher than expected."

"As far as I know, there is no scientific research laboratory in the world that can produce this kind of gallium nitride film using silicon substrates. This means that we have solved a global problem."

“The technology level is at the international leading level.”

Liu Wenshen said this excitedly, and his mood could be said to be mixed.

He still remembered that when he first met Xu Yuan, he was very worried and didn't quite believe it when Xu Yuan told him that there would be progress within two months.

But now, in less than two months, Xu Yuan has successfully developed high-quality gallium nitride thin films.

It is really surprising and unbelievable.

However, this also made him finally understand why Xu Yuan was elected as an academician of the two academies at such a young age.

Even Academician Zhang Guangyi has great trust in him.

It now seems that Xu Yuan's talent is still outstanding even when he crosses over to the field of materials.

Xu Yuan saw Liu Wenshen's performance, but when he heard the result, his expression was still calm. After all, he had known it for a long time.

Then he smiled and said to Liu Wensen, "It seems that it is time for us to tell Academician Zhang the good news."

……

(End of this chapter)