I started with a ship full of max-level veterans, and I'm just a complete noob.

The single crystal furnace was assembled the following morning.

The furnace body of the old vacuum evaporation equipment was reinforced. After the original evaporation electrodes were removed, a graphite crucible support was installed at the bottom, the induction coil was placed around the outside of the crucible, and the top lifting frame was fixed to the furnace cover by two guide rails.

The seed crystal chuck hangs in the center of the furnace opening, with a ground germanium seed crystal less than three centimeters long below it. The tip of the seed crystal has been trimmed into a flat bevel by Lao Sun.

Jiang Ming stood in front of the control panel and divided the heating circuit into three segments: proportional, integral, and differential.

The new furnace has a smaller thermal inertia than the No. 3 furnace, and the atmosphere inside the furnace is more easily affected by changes in opening the lid and gas intake. The parameters originally used for regional purification can only be used as a starting point.

He had Da Liu connect the simulated load first, Fang Xudong checked the temperature sensor and recorder, and Lao Sun removed the worm gear and ran his fingers along each of the copper teeth.

"The gear surface still needs to be ground. After adjusting the speed to a low gear, you can feel a slight vibration in the handwheel."

"Let's take it apart and look at the tooth root first."

Old Sun placed the worm gear on the worktable, and Big Liu shone a kerosene lamp on the tooth groove. Sure enough, he found an uncleaned burr on a meshing surface.

"It will get stuck here."

Old Sun took out a triangular file, carefully trimmed away the protrusions, and then wiped the toothed surface twice with fine sandpaper before reinstalling it into the transmission box.

After the no-load heating test began, the crucible temperature rose rapidly along the curve. Jiang Ming reduced the integral step to avoid accumulating too much error when the furnace temperature approached the melting point.

The temperature curve on the control panel was shorter than that of furnace No. 3. The power adjustment of the induction coil was only separated by a very short response time. Fang Xudong increased the paper tape speed to fully record each power change.

"850 degrees, the bottom of the furnace is two degrees higher than the opening of the furnace."

"The bottom of the graphite crucible is heated first, and the sensor position is moved downwards."

Jiang Ming instructed Da Liu to loosen the sensor mounting bracket, move the probe to the middle of the crucible, and then asked Fang Xudong to run the heating curve again.

After the second no-load test was completed, the temperature distribution inside the furnace narrowed, the induction power dropped from a high level, and the controller began to make slight corrections near the set value.

In the afternoon, the purified polycrystalline germanium was sent into a clean material tray.

After six rounds of purification, the enriched area at the tail end of the germanium material has been removed. The remaining part is cut into small pieces and placed into a graphite crucible one by one. The total weight in the crucible is controlled according to the capacity of the first batch of tests.

Old Sun put on heat-resistant gloves, fixed the crucible on the bracket, and Jiang Ming confirmed that the seed crystal chuck was in the center of the furnace opening before asking him to close the furnace lid.

Argon gas enters the furnace chamber, and once the pressure reaches the specified range, the heating circuit is activated.

The outer wall of the graphite crucible first turns dark red, the temperature continues to rise toward the melting point, the edges of the germanium block begin to lose their original sharp edges, and the liquid surface slowly spreads at the bottom of the crucible.

Fang Xudong kept watch through the viewing window, writing down the temperature and liquid level on a recording sheet.

"Nine hundred and thirty-eight degrees, the bottom is starting to melt."

"Nine hundred and forty-five, and there is still solid in the center."

Jiang Ming kept the heating power at the current value and waited for the melt to spread out completely before continuing to increase the temperature.

Ten minutes later, the last piece of germanium sank to the surface of the liquid, leaving only a layer of silvery-gray melt in the crucible, with slight flow on the surface due to induction heating.

Jiang Ming lowered the seed crystal.

Old Sun turned the lifting handwheel, and the seed crystal chuck slowly descended along the guide rail. When the tip approached the surface of the melt, Fang Xudong pushed the light shield next to the viewing window open by one notch.

When the tip of the seed crystal contacts the liquid surface, the brightness changes accordingly, and the melt climbs a short distance upward along the seed crystal.

"Contact is stable, and the seed crystal has already held the melt."

Jiang Ming glanced at the record sheet.

"The lifting speed is one millimeter per minute, and the rotation speed is fifteen revolutions per minute."

Old Sun handed the handwheel to the transmission mechanism, and Big Liu turned on the rotary motor. The seed crystal began to rise slowly, forming a meniscus between the liquid surface and the seed crystal.

For the first five minutes, the meniscus edge remains smooth, the melt replenishes from all sides towards the center, and the solid-liquid interface extends upward in an arc shape.

Fang Xudong observed the crescent moon through a viewing window and marked each shape change next to the paper strip.

"The linear pull is 15 revolutions per minute, and the furnace temperature is 943.8 degrees Celsius."

"continue."

Jiang Ming placed the melt temperature and the seed crystal position on the same piece of paper and observed whether the temperature curve was synchronized with the change of the meniscus.

In the sixth minute, the seed crystal had been pulled out five millimeters, with a metallic gray surface and smooth sides.

At the seventh minute, a short, sharp zigzag line appeared on the right side of the crescent.

Fang Xudong circled the area inside the observation window with a pencil.

"The right edge is no longer round."

Old Sun placed his hand on the transmission mechanism. The rotary motor was still working, but the sound of the worm gear turning was irregularly intermittent.

In the eighth minute, polygonal ridges appeared on both sides of the crescent, and the brightness at the point where the liquid surface and the crystal came into contact began to disperse.

The surface of the newly pulled germanium rod turns milky white, the metallic luster recedes from one edge, and the fine grain texture extends upwards along the side.

"Cease all calls."

Jiang Ming pressed down the lifting handwheel.

Old Sun cut off the rising mechanism, and the seed crystal stopped below the furnace opening, while the rotation continued at a low speed.

Jiang Ming stared at the milky white crystal, then asked Fang Xudong to record its current length.

"It switched to polycrystalline at the eighth minute and could no longer grow."

Old Sun inspected the transmission box, his fingers touching the worm gear housing.

"The gears jammed a bit when we turned at a certain angle just now."

"How long was the pause?"

"I could feel the handwheel in about 0.2 seconds."

Da Liu disassembled the transmission box, took out the worm gear copper teeth, and the light fell on the root of the teeth, where there was a piece of burr that had not been cleaned properly. After meshing, it pressed a shallow mark on the tooth surface.

Jiang Ming removed the failed crystal from the chuck and cut it longitudinally after the temperature dropped.

The front section of the fracture surface maintains a continuous orientation. In the milky white region, the grains disperse into several groups from a main direction and continue to expand outward, eventually forming intersecting grain boundaries.

Fang Xudong used a polarizing microscope to examine the cross-section and recorded the positions of orientation changes.

"It starts to become chaotic after five millimeters, which corresponds to the time when the rotation becomes sluggish."

Jiang Ming arranged the cross-sectional diagram and temperature curve side by side.

"Fluctuations in rotational speed cause changes in melt flow, and the temperature gradient at the solid-liquid interface reverses accordingly, leading to the formation of new crystal nuclei in the supercooled region."

Old Sun put the worm gear back on the worktable.

"Fix the mechanical part first. Fifteen revolutions per minute might be too fast; the temperature field can't handle it."

Jiang Ming looked at the milky white side of the failed sample, raised his hand and wrote down two sets of parameters on the paper.

"The second time, reduce the rotation to twelve revolutions per minute and the lifting speed to 0.8 millimeters per minute to preserve the interface."

Da Liu handed the repair tools to Lao Sun, who then reworked the worm gear root and added a thin shim to the drive shaft to reduce axial movement.

When charging the second batch, the weight of the purified germanium material was 10% less than the first time. Jiang Ming hoped to reduce the height of the melt so that the seed crystal contact surface was closer to the bottom of the crucible, thus shortening the temperature field transmission path.

The argon flow rate was recalibrated, and after the melt temperature was raised to 945 degrees Celsius, the seed crystal temperature dropped again.

This time, instead of directly handing it to the motor, Lao Sun first used a handwheel to rotate the seed crystal. Only after the contact point stabilized did he allow the rotating mechanism to run at a low speed.

"Twelve revolutions per minute, lifting rate 0.8".

Fang Xudong wrote the two data points at the top of the record sheet.

As the seed crystal leaves the surface of the melt, the meniscus slowly elongates. For the first ten minutes, the interface remains smooth. Although the crystal diameter changes, the edges are still within a range that can be corrected.

The furnace temperature curve shifted upward by 0.2 degrees, the controller replenished a small amount of power, and the meniscus returned to its original shape.

In the fifteenth minute, the germanium crystal had grown to more than one centimeter, with a uniform metallic gray surface.

In the twentieth minute, the seed crystal position continued to rise, the melt in the crucible gradually decreased, and the solid-liquid interface continued to advance in the same direction.

Old Sun placed his hand on the transmission box, and the gears turned smoothly, with the handwheel markings matching the positional changes on the recording paper.

Forty minutes later, Jiang Ming told him to stop pulling and continue rotating until the crystal completely separated from the melt before cooling it down.

The germanium rod was removed; it was 32 millimeters long, with smooth sides, a metallic sheen, and a short growth mark around its base.

Fang Xudong smoothed the end face and observed it under a polarizing microscope.

Under the microscope, the cross-section of the crystal showed a continuous change in brightness and darkness in the same direction, and the dispersed grains found in the first batch could not be found.

"All of them share the same orientation."

Old Sun closed the toolbox.

"It's done this time."

Jiang Ming didn't respond. He placed the germanium rod in the cork clamp and drew measurement marks along its length.

"Single crystal growth is only the first step; we need to measure the resistivity first."

Fang Xudong moved the four-probe measuring station to the side of the table and adjusted the current source and voltmeter.

"Every two millimeters?"

"Measure every two millimeters, from beginning to end, and the data must be able to connect with the regional purification curve."

Lin Lanying stood to the side, looking at the 32-millimeter-long germanium single crystal, her finger gently pressing a corner of the recording paper.

"The length of this crystal has exceeded the length of the sample we originally prepared for observation."

Whether it can be used to make devices depends on the impurity distribution.

Jiang Ming fixed the single crystal onto the fixture, and the first set of probes landed on the head end face. The voltmeter pointer moved as the current source was turned on.

Fang Xudong picked up a pencil and waited for the reading to stabilize.

"First point at the head, begin recording."