4 ms·

Something that I've never found a satisfactory answer to when I've read about this method before has been the source for seed crystals. Where did the 'original'

Something that I've never found a satisfactory answer to when I've read about this method before has been the source for seed crystals. Where did the 'original' seed crystal come from in this process? I suppose once a new crystal with proper structure fabricated, you could use the newly created crystal as seed for further creations. Usually this was glanced over in my textbooks on silicon fab while in college.

pmahoney 7y ago
The article states the process was discovered > while investigating the crystallization rates of metal, Czochralski dipped his pen into molten tin instead of an inkwell. That caused a tin filament to form on the pen’s tip And later, describes the process for silicon > Once the silicon melted, he placed a small piece of polycrystalline material—a seed crystal It seems then, that the seed crystal is not anything special. A typical piece of metal (such as a the pen tip) is made of up multiple single-crystal "grains" with non-crystalline "grain boundaries" between them; this is a polycrystalline material. The question then is, why does only a single crystal form, rather than multiple crystal filaments oriented at different directions according to whichever grain contacted the starting point of the filament...
- silizium 7y ago
  > The question then is, why does only a single crystal form, rather than multiple crystal filaments oriented at different directions according to whichever grain contacted the starting point of the filament... The silicon wants to be in the lowest energy state and it does so by forming a face centered cubic crystal (diamond structure). The formation of crystals depends on the cooling rate. If matter cools to fast, it can't form a crystal structure.
- HelloNurse 7y ago
  If the start of crystallization is sufficiently difficult, growth begins with only one random grain and when the other grains start growing, a significant time later, they find themselves shut off by previous growth.

pmahoney 7y ago

The article states the process was discovered > while investigating the crystallization rates of metal, Czochralski dipped his pen into molten tin instead of an inkwell. That caused a tin filament to form on the pen’s tip And later, describes the process for silicon > Once the silicon melted, he placed a small piece of polycrystalline material—a seed crystal It seems then, that the seed crystal is not anything special. A typical piece of metal (such as a the pen tip) is made of up multiple single-crystal "grains" with non-crystalline "grain boundaries" between them; this is a polycrystalline material. The question then is, why does only a single crystal form, rather than multiple crystal filaments oriented at different directions according to whichever grain contacted the starting point of the filament...

silizium 7y ago
> The question then is, why does only a single crystal form, rather than multiple crystal filaments oriented at different directions according to whichever grain contacted the starting point of the filament... The silicon wants to be in the lowest energy state and it does so by forming a face centered cubic crystal (diamond structure). The formation of crystals depends on the cooling rate. If matter cools to fast, it can't form a crystal structure.
HelloNurse 7y ago
If the start of crystallization is sufficiently difficult, growth begins with only one random grain and when the other grains start growing, a significant time later, they find themselves shut off by previous growth.