How to grow @UTAustin Silicene Transistors and Group 4 Super-conducting Processors and Batteries

It may not yet be the end of the line for the use of Silicon in making Transistors.

This as Dr. Deji Akinwande, a computer engineer at the University of Texas at Austin, has developed a way to use a form of Silicon called Silicene to make Transistors as reported in the article “Atom­Thick Silicon Makes Crazy­Fast Transistors”, published February 2, 2015 by Katherine Bourzac, MIT Technology Review.

Silicene is basically a material made of layers of covalently bonded Silicon atoms that is one atom thick, very similar to graphene. Because Silicon is in Group 4 in the Periodic Table, it has four (4) Valence Electrons in its outer shell. Three (3) of these valence electrons are covalently bonded to three (3) other valence electrons in other Silicon atoms, forming a flat sheet of Silicon atoms in a macromolecule as shown below.

As each of the covalently bonded Silicon atoms has 1 (one) remaining valence electron left, the sheets of Silicene can bond with another sheet of Silicene to form an even bigger 3D macromolecule made up of millions of layers of Silicene.

This gives this macromolecule, Silicite, some amazing physical and electrical properties similar to graphite, which has the same structure made up of atom thick layers of covalently bonded carbon that are also covalently bonded in a 3D Macromolecule.

In 2007, Dr. Lok Lew Yan Voon of Citadel Military College of South Carolina had done some theoretical calculations of the properties of Silicene, he originally predicted that Silicene should have the same electrical properties as Graphene.

Graphene is known to have superconducting properties due to its orderly arrangement of atoms and electrons, the main focus of the research of one of Dr. Deji Akinwande detractors, Dr. Fengnian Xia, an electrical engineer at Yale University.

Still, my focus isn't so much on Silicene and this new method to grow it to make processors. Rather, I’m more interested in what it logically implies for Group 4 elements n the Periodic Table.

How to grow Silicene - Not every macromolecule is born with a silver spoon in its mouth

Unlike Graphene, Silicene isn't naturally occurring, as it has to be grown on a substrate made up of a sheet of silver. However, unlike Graphene, which is naturally occurring, Silicene is unstable when exposed to air due to the longer bond lengths created by the repulsion from its larger nucleus.

Its bonds are also easily broken by the addition of energy, such as from heating or radiation, as the Covalent Bond Energy for Silicene is very low. Dr. Deji Akinwande devised a clever method to keep the Silicene macromolecule stable; the entire macromolecule is grown on the silver substrate via vapour deposition.

The Silver Substrate acts as an electrons pump to push more electrons into the Silicene macromolecule. Thus, the macromolecule is kept stable when exposed to air and the very reactive Oxygen (O₂) molecules.

To protect it from destabilizing, the atom-thick Silicene growing on the Silver substrate is  coated with an unreactive layer of aluminum oxide (Al₂O₃), basically forming a Silicene sandwiches shown below.

To make transistors, the entire Silicene sandwich is them peeled off from the surface it was on during growth via vapour deposition, most likely in a plastic Petri dish inside of a vacuum chamber. The sandwiched is then flipped over with the silver side up.

Then etching methods, similar to those used in making Transistors and Processors are used etch out the Transistors and create complex TTL (Transistor-Transistor Logic) based circuits. In creating the circuit pathways, the Silver is used as the contacts to connect with the Silicene to external circuits for testing purposes.

This etching process cannot be chemical, due to the unstable nature of the Silicene macromolecule. Most likely it might involve the use of some intense focused radiation, such as a UV laser or a high-energy Femtosecond laser as chronicled in my blog article entitled “University of Southampton and Eindhoven's University write and read Data to Quartz Crystal - Eternal Storage borrowed from Superman Man of Steel”.

This makes sense as you'd need such a powerful laser to move atoms into place, cutting trenches and building up mountains on a Nanoscopic scale as was done by Dr. Chunlei Guo and his colleague at the University's Institute of Optics as published back in January 2015 to create Hydrophobic metallic surfaces as detailed in my blog article entitled “Dr. Chunlei Guo's Hydrophobic Surfaces - Nanoscopic Architecture imparts Musical properties at a Nanoscopic Level”.

Once the etching process is finished, the TTL circuit than then be packaged using the same standard vacuum packaging techniques used to make regular TTL  Circuits. Graphene and its tubular counterpart, CNT (Carbon nanotubes), are already being used in the making of transistors and even Processors for testing out the amazing properties of CNT’s.

This is based on the work of a research team at Stanford University published back in September 2013 as reported in my blog article entitled “University of Stanford Designs a Proof-of-concept Processor using Carbon Nanotubes - Practical option to expand Moore’s Law along with Optical, Quantum and Neural Net Processors”.

It might therefore be possible to roll Silicene into tubes of SNT (Silicon Nanotubes) that would also theoretically have the same exact electrical properties as CNT. Silicene in this form, could then be used to make super-fast low-power and low-noise TTL Logic circuits at the atomic scale, even as complex electronics components such as Processors.

Silicene and Group 4 - Super-conducting Macromolecular Processors possible to continue Moore’s Law

The work of Dr. Deji Akinwande has some deeper implications for Group 4 elements that chemistry buffs should love.

It implies that any Group 4 elements, once arranged in this orderly crystalline macromolecular pattern, will exhibit varying degrees of room temperature Super-conductivity and fast charge carrying capabilities. In fact, this might be true for ANY element in the Periodic Table that exhibits covalent bonding, not just Carbon, given the right substrate conditions.

Possibly, as the molecular mass of the atoms increase as you go down Group 4, you might even see super-capacitors at room temperature, as the orderly arrangement of atoms makes it possible to have circuits that require little electrical power and have low noise characteristics. This would make them great storage cells for electricity, as one aspect of super-conductivity is the ability to continue carrying a current once the external voltage source is removed.

The other Group 4 elements cans also be bonded into a macromolecule of a similar structure and made into layers of macromolecule, namely:

1.      Titanium

2.      Germanium

3.      Zirconium

4.      Tin

5.      Hafnium

6.      Lead

7.      Neodymium

8.      Lutetium

9.      Uranium

10.  Lawrencium

The other Group 4 Elements tend to be mainly Transitional, Metallic Bonding and radioactive in nature. They also have larger atomic radii and increasing atomic nuclear mass making this covalent bonds, is possible, even more delicate and easily broken.

This due to the repulsion forces exhibited by their positively charged nucleus, the force of which must be overcome. However, I’ve theorized that it’s possible to use Group 2 Elements such as Beryllium to bind these larger molecules into the same macromolecular structure a shown below.

Beryllium, which is very reactive and has a two (2) valency electrons in its outer shell, can act as a covalent bridge, strengthening the covalent bond between the two (2) Group 4 atoms as they have a smaller nuclear mass. In so doing, it would keep the macromolecule stable and also increase the super-conductivity at room temperature, being as it can contribute its extra electrons to the conductivity sea of mobile electrons.

However, due to the reactivity of Beryllium, creating this macromolecule would have to be done in a vacuum. Also, we have to develop techniques to bind the beryllium atoms to form the pattern shown, requiring techniques that can build the material atom by atom.

A suitable substrate that is a transitional metal that is high in the electrochemical series and has an excess of electrons such as Copper can be used as a suitable substrate. 

Graphene and its tubular counterpart, CNT (Carbon nanotubes), are already being used in the making of Transistors and even Processors, based on the work of a research team at Stanford University published back in September 2013 as reported in my blog article entitled “University of Stanford Designs a Proof-of-concept Processor using Carbon Nanotubes - Practical option to expand Moore’s Law along with Optical, Quantum and Neural Net Processors”.

It might therefore be possible to roll Silicene into tubes of SNT (Silicon Nanotubes) as well as the other Group 4 Macromoleucules, if they were also made, so that they would also theoretically have the same exact electrical properties as CNT.

The work of Dr. Lok Lew Yan Voon of Citadel Military College of South Carolina has been made practical by Dr. Deji Akinwande of the University of Texas at Austin. More work, both theoretical and practical, has to be done to explore other 2D Macromolecular and 3D Macromolecular properties of the heavier Group 4 Elements.

They may have exciting implications for making designer molecules with special properties, such as building the next generation High speed, low-Power Low noise Processors and Room-temperature Super-conducting Batteries