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Side-quest : "what the heck is 'epigraphene'?": > Graphene’s original promise to succeed silicon faltered due to pervasive edge disorder in lithographically pa

Side-quest : "what the heck is 'epigraphene'?": > Graphene’s original promise to succeed silicon faltered due to pervasive edge disorder in lithographically patterned deposited graphene and the lack of a new electronics paradigm. Here we demonstrate that the annealed edges in conventionally patterned graphene epitaxially grown on a silicon carbide substrate (epigraphene) are stabilized by the substrate and support a protected edge state. From https://www.nature.com/articles/s41467-022-34369-4 https://www.nature.com/articles/s41467-022-34369-4

jpgvm 3y ago
> epitaxially Is the keyword you are after. Basically this is a vapour deposition technique of some sort, almost certainly using MBE (molecular beam epitaxy) to grow the graphene on the silicon carbide substrate.
- adrian_b 3y ago
  While MBE is the best method for many kinds of materials, in this special case a completely different method has been used. Half of silicon carbide is carbon, and by heating silicon carbide at very high temperatures and low pressures the silicon atoms that are close to the surface evaporate, leaving a superficial layer made of carbon. By applying a certain thermal treatment, the carbon layer crystallizes into a layer of monocrystalline graphene. Like for many other great ideas, after someone succeeds to do it it seems weird that nobody has tried to do such a thing before. However it is likely that the parameters of the process are very critical for obtaining a layer with good characteristics, so a large number of experiments have been necessary to determine them.
  - jpgvm 3y ago
    Oh wow! I guess I have a new rabbit hole to go down. Thanks for the info, I just presumed it would be MBE.
adrian_b 3y ago
For those who are not familiar with semiconductor technology, epitaxial growth is one of the most important technological processes that are used in it. Epitaxial growth means the deposition of a monocrystalline layer of some material over a substrate (i.e. a wafer) that is also a single crystal. Most methods of layer deposition create polycrystalline layers. In order to succeed to grow a monocrystalline layer it is necessary for the deposited material and the substrate material to be compatible in certain properties and the growth must be done in certain carefully controlled conditions. Many semiconductor materials can be used only if it is possible to grow them epitaxially, because either it is impossible to make big enough crystals by other methods, or the big crystals have various undesirable properties, for instance low thermal conductivity. The fact that the team from Georgia Tech, together with the Chinese team from Tianjin University, have achieved epitaxial growth of graphene over a substrate with excellent properties for semiconductor device fabrication, like silicon carbide, changes completely the prospects of using graphene in practical semiconductor devices.

jpgvm 3y ago

> epitaxially Is the keyword you are after. Basically this is a vapour deposition technique of some sort, almost certainly using MBE (molecular beam epitaxy) to grow the graphene on the silicon carbide substrate.

adrian_b 3y ago
While MBE is the best method for many kinds of materials, in this special case a completely different method has been used. Half of silicon carbide is carbon, and by heating silicon carbide at very high temperatures and low pressures the silicon atoms that are close to the surface evaporate, leaving a superficial layer made of carbon. By applying a certain thermal treatment, the carbon layer crystallizes into a layer of monocrystalline graphene. Like for many other great ideas, after someone succeeds to do it it seems weird that nobody has tried to do such a thing before. However it is likely that the parameters of the process are very critical for obtaining a layer with good characteristics, so a large number of experiments have been necessary to determine them.
- jpgvm 3y ago
  Oh wow! I guess I have a new rabbit hole to go down. Thanks for the info, I just presumed it would be MBE.

adrian_b 3y ago

For those who are not familiar with semiconductor technology, epitaxial growth is one of the most important technological processes that are used in it. Epitaxial growth means the deposition of a monocrystalline layer of some material over a substrate (i.e. a wafer) that is also a single crystal. Most methods of layer deposition create polycrystalline layers. In order to succeed to grow a monocrystalline layer it is necessary for the deposited material and the substrate material to be compatible in certain properties and the growth must be done in certain carefully controlled conditions. Many semiconductor materials can be used only if it is possible to grow them epitaxially, because either it is impossible to make big enough crystals by other methods, or the big crystals have various undesirable properties, for instance low thermal conductivity. The fact that the team from Georgia Tech, together with the Chinese team from Tianjin University, have achieved epitaxial growth of graphene over a substrate with excellent properties for semiconductor device fabrication, like silicon carbide, changes completely the prospects of using graphene in practical semiconductor devices.