Chapter 842 Chief Engineer Gao's technical route has been changed
After Gao Zhendong finished his speech, Yi Zhonghai announced the end of the ceremony. There was laughter and joy in the yard. People ate and drank!
When it comes to eating, Gao Zhendong always feels that using the Engel coefficient (food expenditure/total expenditure) to determine whether one is poor is not very reliable for us. Of course, we are very poor now, but when we were not so poor, we still loved to eat. It is really difficult to evaluate.

Especially when the concept of the Engel coefficient was proposed by Hans, Gao Zhendong always felt that the persuasiveness of this matter had to be discounted. Of course, if it was proposed by John Bull, it would be even more difficult to justify.

As for John Bull and other things, no one wants to spend more money on food. The Engel coefficient is too high, which means that there is really no way out. You have to eat, and you are indeed poor. As for Hans, the 500,000-mark bread proved that sometimes this index is indeed true.

However, these are just Gao Zhendong's own fantasies and cannot be relied upon.

When toasting, Qin Huairu pulled Sha Zhu aside and, contrary to the usual practice of giving one glass to each table, specifically toasted Gao Zhendong and his wife.

"Chief Engineer Gao, this glass of wine is for thanking you. Without your help, I don't know what our family would be like."

Qin Huairu knew it herself. Even though Gao Zhendong seldom interacted with her except for official business, the few interactions they had were only brought up by Sha Zhu.

But if Gao Zhendong hadn't helped her out at critical moments, she wouldn't have been able to survive the bullying of her child, let alone the most basic issues of work and food. And Gao Zhendong's brilliant suggestions between her and her master, if not saving her family from danger, at least saved her from a desperate situation.

The neighbors knew a lot about these things, so they didn't have any opinion about Qin Huairu pulling Sha Zhu to toast Gao Zhendong and his wife, and they didn't think Qin Huairu was trying to flatter Gao Zhendong.

At such a happy moment for her, if this glass of wine was disrespectful, it would seem like someone looked down on her.

Gao Zhendong and his wife drank wine and water respectively, and finished the cup with Sha Zhu and his wife. Gao Zhendong smiled and said, "Those are all small matters. If you can live a good life in the future, that's better than anything else."

Sha Zhu was unwilling to be lonely: "Hey, don't worry, I will definitely live a good life."
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Gao Zhendong was in the office, waiting for the comrades from Factory 1218 who had made an appointment with him to come. The comrades from Factory 1218 were very efficient and in a hurry. Not long after receiving the notice from the department, they had made all the preparations and were busy making an appointment with Gao Zhendong. They all knew that Chief Engineer Gao was very busy, so the sooner the better.

The comrades from Factory 1218 had not arrived yet, but Tang Shaohui came to see him with the latest progress of solar panels.

"Chief Engineer Gao, during the course of our work, we found that there are some areas that can be improved, but there are still some problems with the final result." The improvements he mentioned refer to the improvements in Gao Zhendong's technical route. When he said this, he no longer had the nervousness he had when he first proposed the idea of ​​making progress on both single crystal and polycrystalline. Chief Engineer Gao is not that kind of person. It feels comfortable to work under his guidance.

Sure enough, Gao Zhendong was delighted when he heard his words: "Great! Tell me about it."

“You mentioned that when making textures on the surface of polycrystalline silicon, you can use photolithography and laser engraving technology. We found that there are some areas that can be improved.”

Polycrystalline silicon is multi-crystalline and has multiple crystal orientations on its surface. It cannot be texturized using the NaOH solution commonly used for single-crystalline silicon. It is much more complicated. Therefore, in terms of texturizing, polycrystalline silicon is the focus of their research, while single-crystalline silicon can be processed by directly copying the technology given by Gao Zhendong.

They also copied polysilicon, but they made new discoveries in the process of copying.

Tang Shaohui took out a piece of information and reported it to Gao Zhendong very happily.

"Look, this is the statistics we collected during the research process. The cost of photolithography is very high, and the accumulated cost is huge. We also want to solve this problem. After repeated research and experiments, we accidentally mixed hydrofluoric acid used for silicon wafer etching and some types of film fixer waste containing silver ions together during the experiment. We also spilled it on the polycrystalline silicon wafer. It took a long time to discover it."

As for laser engraving, that was not something Tang Shaohui could consider, so he skipped it directly.

The things he mentioned were all commonly used in their experiments. When talking about the mistakes made by the experimental team, Tang Shaohui was not frustrated, but even had a light in his eyes. Gao Zhendong knew that the classic scene of "a mistake leads to a new path" in scientific research had probably happened.

As he expected, Tang Shaohui's next words confirmed his guess: "Based on the idea of ​​trying whatever method you mentioned, we splashed it on anyway. We observed the surface of these silicon wafers under a microscope and found a very surprising phenomenon. Small holes were etched on the silicon wafers. Although the distribution, overall quality, and uniformity did not meet the requirements, the scale was probably in the same order of magnitude as required by the process." Huh? Hydrofluoric acid was originally used to etch silicon wafers. In theory, except for the uneven etching caused by the uneven polycrystalline grain boundaries, the reaction speed of other places should be basically the same. Why do silicon wafers containing silver ions have extremely small holes?
Gao Zhendong was very keenly aware of the phenomenon that Tang Shaohui mentioned. It just so happened that what he had been researching most recently was the synthesis of organic matter. Although it was organic chemistry and what Tang Shaohui was talking about was inorganic chemistry, some things between them were similar.

Gao Zhendong's enhanced brain was so powerful that he immediately combined his recent work and answered quickly: "Is it a series of extremely small holes? Catalytic reaction?"

Gao Zhendong's two sentences were extremely brief, but they astounded Tang Shaohui.

"Ah? You guessed it already? Chief Engineer Gao, you are amazing!"

Tang Shaohui's words had nothing to do with flattery. He truly admired Gao Zhendong from the bottom of his heart. He didn't know the process or the result, but he grasped the core of the problem just by describing it bit by bit, and in a field that was theoretically unfamiliar to him.

Mr. Xiang from a chemical engineering institute: Actually, he is not unfamiliar with this.

"You are right, it is catalysis! We have also asked teachers from related majors to study it. Once they find a phenomenon, it is much easier for them to reverse the principle. In this case, silver ions are the catalyst for the reaction between hydrofluoric acid and silicon wafers. Silver ions form an electrolytic channel with silicon, reducing silver, and oxidizing silicon to obtain silicon dioxide. The reaction between silicon dioxide and hydrofluoric acid is much faster than the reaction between silicon and hydrofluoric acid, thus forming holes. At this time, the reduced silver will sink on the surface of the silicon wafer, further digging out holes! It becomes small holes! Although the scale is still a little insufficient, it is very close to our goal."

What Tang Shaohui said was a bit complicated, but Gao Zhendong understood it. To use a more vivid metaphor, it is like spreading a lot of hot iron balls on the ice. These iron balls will sink and burn holes on the ice. The only difference is that the reason why the iron balls sink is physical, while the reason why the silver sinks is chemical, or electrochemical.

"Great! You have found a new process direction." Gao Zhendong was very happy. Although the size of the hole was a problem, at least it was a direction.

Seeing Gao Zhendong's high evaluation of this discovery, Tang Shaohui was also very happy: "We worked with the chemistry professors in the school to find a way to evenly deposit silver ions on the silicon wafer, remove these silver ions and elemental silver after a period of time after the reaction begins, and then use a mixture of hydrofluoric acid and nitric acid to corrode and expand these pores. In the end, we basically got the texture we needed, and the cost was greatly reduced, the process was simple, and the equipment requirements were low."

In this way, the size of the etched hole is controlled by the reaction time, which is much simpler.

Photolithography requires the size control of the texture, and has high requirements for equipment. However, in the method mentioned by Tang Shaohui, the size of the holes is controlled by chemical processes in principle, and has little to do with the equipment.

Gao Zhendong couldn't help but patted Tang Shaohui on the shoulder and said, "Well done! In theory, your method only requires a reaction tank, and no special equipment is needed. The requirements for equipment and technology are simply compressed to the point where they cannot be increased!"

Tang Shaohui also laughed. Chief Engineer Gao hit the nail on the head. The core equipment of this method was really as simple as a reaction tank. Of course, it was not that simple in reality, but compared with photolithography and laser engraving, it was really a world of difference.

But he didn't laugh for long.

"But there are still problems. Theoretically it works, but it doesn't work for mass production. We are also considering solving this problem, but we haven't been able to solve it yet. The quality of the suede we produce is unstable. Some batches are good and some are bad. Some areas are good and some are bad. In short, it is impossible to mass produce stably."

Gao Zhendong was not so worried about this. He thought, "Just take it slow. Believe in your comrades. At least they have found the right general direction."

"It doesn't matter. It will be easy if we understand the principle. There is always a way. As for the polysilicon texturing, we should follow the path you found. This path has much better prospects. Don't be afraid of the slow process. I will take responsibility for any problems." Gao Zhendong immediately patted his chest and straightened his shoulders to take up the responsibility. Polysilicon is not used in space, but for popular use. There is plenty of time to polish it slowly, and the lower the cost, the better.

Gao Zhendong's approach of patting his chest and taking responsibility made Tang Shaohui feel very comfortable. What is the purpose of being a leader? To solve problems and shoulder them. Chief Engineer Gao did a good job in these two aspects, which convinced everyone in their research group.

(End of this chapter)