Volume 1: Student Life Chapter 259 p-type, n-type, and co-doping
Chen Zhou first summarized the 10 sets of experimental data compiled by Shen Jing, and then began to refer to the research methods of thin film preparation technology.
First, go through a large amount of literature, list all the problems, and look for solutions.
Combined with these 10 sets of experimental data from the 43 institutes, trial and error were carried out using the wrong question collection.
As for Shen Jing, Chen Zhou assigned him the same task as Zhang Yifan.
That is, he needs to work with Fang Jieming to build an analytical model for the doping experiment.
"The choice of boron source for p-type doping is B(CH3)3, which should be no problem."
“Because B(CH3)3, as a boron source, is conducive to the incorporation of boron atoms into substitutional positions in the diamond lattice, it can improve the incorporation efficiency of boron…”
"…The influence of different diamond substrate crystal planes on the carrier mobility of boron-doped diamond prepared…"
"…According to experimental data and literature, when boron-doped diamond layers are prepared on single crystal diamond substrates with (100), (110), and (111) faces…"
"…the lattice defects of the (111) and (110) diamond substrates capture a large number of boron atoms, reducing the incorporation efficiency of boron atoms. In addition, there is strong impurity scattering, which makes the mobility lower than that of the (100) diamond substrate…"
"so……"
Chen Zhou's thoughts were very clear.
All the content about p-type doped diamond was constantly filtered and screened in his mind.
He is turning his thoughts into a clear direction.
At the same time, the pen in Chen Zhou's hand was constantly writing on the draft paper.
To outsiders, what he wrote on the draft paper might not seem to have any pattern.
But in Chen Zhou's eyes, he is getting closer to his goal step by step.
11 a.m.
Peng Fei came to this small office.
The excitement on his face had not yet completely faded, and his entire mental state was still extremely excited.
When Chen Zhou saw his appearance, he was a little worried. Would this man suddenly... collapse?
But before Chen Zhou could say anything, Peng Fei said, "I have completed all the tasks you assigned to me! I have sent all the information to the computer in front of you through the intranet!"
Chen Zhou minimized the page on his computer, searched it, and saw the information compiled by Peng Fei.
Chen Zhou looked up and said to Peng Fei: "I saw it."
Peng Fei walked to Chen Zhou at this time and just looked at Chen Zhou without saying anything.
Chen Zhou looked up at him strangely: "What's wrong?"
Peng Fei then said, "Is there anything else I can help you with?"
Seeing the gleam in Peng Fei's eyes, Chen Zhou couldn't help but smile. Could this guy be addicted to helping others?
Gently shaking his head, Chen Zhou said, "Not for now."
After hearing Chen Zhou's words, Peng Fei felt lost for a moment.
Noticing the change in Peng Fei's expression, Chen Zhou thought for a moment and added, "I suggest you go and rest first, as there will be a lot of things to do later."
Hearing this, Peng Fei immediately looked at Chen Zhou and said quickly: "No problem! I'll go to bed after dinner!"
At noon, Chen Zhou and Shen Jing also had a simple lunch in the cafeteria of Institute 43.
During the meal, Shen Jing couldn't help but joked: "Chen Zhou, that Mr. Peng is almost your fanboy..."
Chen Zhou didn't say much about this.
It doesn't matter if you are a fan or not, the main thing is that I feel like I have a helper, which is really nice~
After lunch, after a short break of ten minutes, Chen Zhou sat in front of the computer again.
The problem of p-type doping is relatively simple, and he has already found the right direction.
After thinking for a while, Chen Zhou looked at Shen Jing and asked, "Senior, how is the analysis model you built?"
Shen Jing turned around and said, "It's still a little bit short. Because the model you requested must be targeted, we have fully considered all aspects of the experiment to construct the p-type doping, n-type doping, and co-doping models. But it's almost done."
"Okay." Chen Zhou responded and said no more.
Since Shen Jing and Fang Jieming have already caught up, let's start with the trial and error of p-type doping in the afternoon.
Let’s put aside the issue of n-type doping and co-doping for the moment.
In the collection of wrong questions, the content about the theoretical research on p-type doping experiments has experienced a parabolic trend.
In the morning, when Chen Zhou just started to study the p-type doping problem, the wrong questions were printed out like a printing press.
All the content that Chen Zhou had read was printed on it until it reached a peak.
Later, as Chen Zhou studied the problem more deeply, the contents recorded in the collection of wrong questions began to change.
Some old content is overwritten by new content, while some content disappears completely.
When old content is covered by new content, it means that the research direction is clear.
The disappearing content means that Chen Zhou has solved the corresponding problem.
Now, the collection of wrong questions is about to stage a parabolic trend again.
"Selection of crystal planes for diamond substrates..."
"Reaction pressure, temperature..."
"The doping concentration of the boron source..."
Combining the 10 sets of experimental data already completed by the 43rd Institute, Chen Zhou began trial and error in the p-type doping experiment.
An hour later, Chen Zhou took out a new piece of draft paper and wrote down a series of experimental parameters on it.
Then he stood up and walked to Shen Jing, throwing the draft paper to Shen Jing.
After Shen Jing got the draft paper, he was slightly stunned, and then began to communicate with Fang Jieming to conduct model analysis.
Chen Zhou returned to his seat and sat down again.
Next, it is time to consider the issue of n-type doping and co-doping.
The problems of n-type doping and co-doping are much more difficult than those of p-type doping.
"The first realization of diamond n-type doping was carried out on a (111) diamond substrate, and the sample exhibited n-type semiconductor conductivity over a wide temperature range..."
"At a temperature of 500K, the Hall mobility is 23cm2/(V·s)..."
"However, compared with the (111) surface single crystal diamond substrate, which is difficult to polish, has many defects and is small in size, the (100) surface oriented substrate has an atomic-level flatness, few defects, and the quality of the epitaxial film is also better than that of the (111) surface substrate diamond..."
"But this is not absolute, and the problem of the crystal surface is not the most critical factor..."
Thinking of this, Chen Zhou stopped writing and habitually tapped on the draft paper.
This is how Chen Zhou reacts when his thoughts are blocked.
"Let's review the literature again..."
Thinking of this, Chen Zhou put down the pen in his hand and turned his gaze to the computer screen again.
The scroll wheel of the mouse in your hand keeps sliding, and the content on the screen keeps changing.
But Chen Zhou didn't even blink.
He has already gone through these contents.
Now when I look at it again, I am just trying to see if I have missed anything.
So as to open up a gap for your blocked thinking.
“What is the phosphorus doping concentration?”
"Electron scattering mechanism?"
"That's not the content of this part..."
"...1.7 eV?"
"How could I forget this data!"
When Chen Zhou saw this content, his eyes brightened instantly.
N-type doping, or phosphorus-doped diamond, is difficult.
This is because phosphorus atoms are larger than carbon atoms and are difficult to embed into the diamond lattice.
When phosphorus atoms enter the diamond lattice, they cause the lattice to distort, affecting the configuration, bond type and charge distribution in the diamond.
There are a large number of vacancies in phosphorus-doped diamond, which will also form phosphorus-vacancy defects with strong binding force with phosphorus atoms.
The energy level of this defect is located at about 1.7 eV at the bottom of the diamond conduction band, which can compensate the donor and hinder the ionization of phosphorus atoms.
This makes it difficult to obtain high-quality phosphorus-doped diamond films.
Although the energy level of phosphorus is 0.58 eV below the bottom of the conduction band, this defect still exists.
"Filling the gap..."
Chen Zhou's hands moved faster and the mouse wheel kept sliding.
Chen Zhou pulled the content on the screen to the co-doping part.
[The nitrogen atom is in a substitutional position in the diamond lattice, forming a deep donor energy level with an excitation energy of 1.7 eV, which is non-conductive at room temperature...]
[In theory, phosphorus can be used as a shallow donor impurity, but the radius of a phosphorus atom is larger than that of a carbon atom, making it difficult to incorporate into the diamond lattice…]
[Theory shows that the phosphorus-nitrogen co-doping method may be an effective way to overcome the self-compensation of wide-bandgap and ultra-wide-bandgap semiconductors ...]
【……】
Seeing this, Chen Zhou unconsciously slowed down his hands.
If nitrogen atoms can fill the defects, there is room for phosphorus atoms to dope...
Originally, we were planning to solve the n-type doping problem first, but as a result of this thinking, the problem jumped to co-doping?
Because the n-type doping experiment of the 43rd Institute used phosphorus doping.
Therefore, in co-doping, they studied the phosphorus-nitrogen co-doping method.
This also made Chen Zhou connect the two together.
Chen Zhou couldn't help but smile in his heart, but he immediately decided to solve the problems of n-type doping and co-doping together.
In the co-doping experiment, PH3 was first used as the phosphorus source, and N2 was used as the nitrogen source.
However, when these two gases were used in experiments, the results obtained were not ideal.
The resistivity of the prepared doped diamond film is very high.
In subsequent experiments, the choice of phosphorus and nitrogen sources was constantly changed.
A single doping source such as NH4H2P04, which contains phosphorus and nitrogen, has also been used in the research.
However, the resistivity of the obtained diamond film is still very high.
Chen Zhou took another look at the experimental data of the 43rd Institute, and then began to organize the substances that could be used as nitrogen and phosphorus sources on draft paper.
While Chen Zhou was immersed in his research, the sky outside the room had gradually darkened.
"Chen Zhou."
Awakened by Shen Jing's voice, Chen Zhou looked up at Shen Jing in confusion.
Shen Jing pointed to the computer: "The data analysis is complete."
"Oh." Chen Zhou responded, stood up and walked to Shen Jing and took a look.
The results of the analysis were basically the same as what he expected.
"Send it to me and I'll do the final processing."
Shen Jing nodded: "Okay."
Chen Zhou turned around and was about to walk back to his seat when Shen Jing grabbed him and pointed to the lower right corner of the computer screen.
Chen Zhou took a look and was surprised to find that it was already half past six.
After thinking about it, Chen Zhou decided not to work overtime at the 43rd Institute and decided to go back to the hotel and feel more comfortable.
So, the two of them sorted out the information, said something to Peng Fei, and left Institute 43.
Chen Zhou was originally wondering why Peng Fei didn't come to see him all afternoon, but he finally understood when he called.
Peng Fei is currently busy collecting finished diamond film products.
Diamond films prepared using an improved process have been completed.
From what Peng Fei said, Chen Zhou guessed that he would stay up late to work overtime again tonight.
And I don't know if he's alone...
After a simple dinner outside, Chen Zhou and Shen Jing returned to the hotel.
Shen Jing originally planned to follow Chen Zhou to his room as before, but was stopped by Chen Zhou.
"Have a good rest tonight, you'll be busy tomorrow." After saying this, Chen Zhou closed the door and went into the room.
Outside, Shen Jing looked at the closed door and muttered, "Could this be a retreat?"
In the room, Chen Zhou quickly turned on the computer and took out the draft paper and the collection of wrong questions.
"Tonight..."
With just a quick glance, I continued with my thoughts from the afternoon.
Chen Zhou once again immersed himself in the research of n-type doping and co-doping issues.
The stack of brand new A4 draft paper that was specially prepared gradually became thinner over time.
And the pen refills that he had always been worried about were also constantly flowing out on the draft paper at an incredible speed.
The content in the collection of wrong questions is constantly increasing and decreasing.
"No matter what the nitrogen and phosphorus sources are, there is only one purpose..."
"No matter what the system inside the device is, it is always used to produce doped diamond films..."
Chen Zhou's ideas became clearer and the direction gradually became clearer.
In the co-doping experiment of the 43rd Institute, no redundant systems were used as auxiliary systems in the device.
But in fact, if there are other systems to assist, the results may be better.
This was an inspiration to Chen Zhou from a foreign document.
Put the filled draft paper aside, replace it with a new piece of draft paper, and then replace the pen refill with one filled with water.
Chen Zhou wrote on the draft paper :
[In the NiMnCo-C system, P2 N5, carbonyl ion powder and phosphorus powder are mixed under high temperature and high pressure to provide nitrogen and phosphorus sources, and diamond is doped in this way...]
After writing this sentence, Chen Zhou suddenly laughed.
"Such a simple truth, why did I think about it for so long?"
Compared with pure nitrogen-doped diamond, H atoms in the form of sp3-CH3 are more easily incorporated into the phosphorus-nitrogen co-doped diamond lattice, improving the quality of the co-doped diamond.
Because in the phosphorus-nitrogen co-doped system, many defects are generated after the phosphorus atoms are doped, forming hanging bonds of carbon atoms, which helps the hydrogen atoms to be doped into the diamond lattice.
Hydrogen atoms can etch the sp2 phase, which is beneficial to the deposition of high-quality diamond films.
"Once the system and nitrogen and phosphorus sources are determined, the remaining problems in the co-doping experiment will be easy to solve..."
As Chen Zhou spoke, he took a few sheets of draft paper that were placed aside.
This is a parameter study conducted by Chen Zhou for different situations when studying nitrogen sources and phosphorus sources.
This is a good time to verify it.
For general substrate temperature, doping concentration, working pressure, etc., you can quickly get a rough range by trial and error using the wrong question collection.
After verification of the analytical model, go back to the wrong question collection for further trial and error.
That's it!
Once the co-doping problem is solved, the problem of n-type doping will be solved on paper.
