Inside a Soviet-Era Crystal Growth Lab

An elderly scientist welcomed us and began to explain how the machines work. The terminology was too dense for me to follow in real time, but thankfully my friend recorded the lecture. Later, with some research, I managed to reconstruct what was happening here.

These were Czochralski crystal growth machines, also called crystal pullers. Seeing them for the first time was something new for me. I am usually drawn to Soviet monumental art, but in that moment, these machines impressed me just as much. They looked like sculptures from an industrial age when science and technology had their own aesthetic power.

The Czochralski Method

The Czochralski method is the most widely used process for growing large single crystals. It was first developed in 1916 by Polish scientist Jan Czochralski, but it reached its peak during the Cold War, when both the Soviet Union and the West needed perfect crystals for semiconductors and lasers.

Here’s how it works:

• Melting the material – A crucible, usually made of quartz, is filled with extremely pure raw material, like silicon or aluminum oxide, and heated until it melts. The heaters are often made of molybdenum or graphite, materials that can withstand enormous temperatures.
  

• Creating an inert atmosphere – The chamber is filled with an inert gas, most often argon, so that the molten material does not oxidize or react with air.
  

• Pulling the crystal – A small “seed crystal” is dipped into the molten material. The seed is then slowly pulled upward and rotated. As it rises, atoms from the melt attach themselves to the seed’s atomic lattice, gradually building a single crystal, called a boule.
  

• Shaping and control – By carefully controlling the pulling speed and rotation, the scientist can determine the crystal’s diameter and quality.

The result is a large, perfect crystal that can later be sliced and polished for use in electronics, optics, or lasers.

Other Techniques

Not every furnace in the room was a vertical puller. Some appeared to be horizontal multi-zone tube furnaces, which are used in the Bridgman–Stockbarger method or in zone refining. In this approach, the material in a crucible is slowly moved through different heating zones inside a horizontal tube. The gradual temperature change allows crystals to form. This technique was widely used in Soviet laboratories during the 1960s–1970s to produce high-purity semiconductors like silicon and germanium.

The control panels, with their teal-blue dials, gauges, and switches, gave the room an almost retro-futuristic look. Voltmeters and ammeters measured the power going to the heaters. Timers tracked the process. Rows of round indicator lights showed the status of different heating zones. The whole setup looked both old-fashioned and incredibly advanced for its time.

The scientist even showed us pipe-shaped ruby crystals. Holding them felt like touching a piece of history. Ruby crystals were central to the invention of the laser.

In 1964, Soviet physicists Aleksandr Prokhorov and Nikolay Basov shared the Nobel Prize in Physics with American Charles Townes for their theoretical work on masers and lasers — the principle of producing coherent light by stimulated emission. While the first working ruby laser was actually built in the United States by Theodore Maiman in 1960, it was Prokhorov and Basov who laid the theoretical foundation and developed many of the techniques that made such breakthroughs possible.

The furnaces in this institute are not only for semiconductors like silicon wafers. They also produce a range of crystals used in optics and laser technology:

• Garnets (YAG, Y₃Al₅O₁₂): Widely used in solid-state lasers.

• Fluorides (CaF₂, LiF, BaF₂): Essential for UV lenses, infrared windows, and as laser host materials.

• Ruby (Al₂O₃ doped with chromium): The first solid-state laser crystal, still used for research and education.

• Sapphire (pure Al₂O₃): Valued for its hardness, optical clarity, and use as a substrate in electronics.

Walking out of the lab, I felt as if I had stepped back in time. The machines, the smell of heated metal, the sound of water cooling pipes — everything reminded me of the Soviet tradition of merging science, industry, and vision. For me, someone more used to admiring monumental Soviet mosaics and sculptures, these crystal growth machines carried the same sense of power and beauty.

They are not relics. They are still at work, producing crystals for optics and lasers, keeping alive a legacy of scientific craftsmanship that began decades ago and still shines today.