If computer technology continues to evolve at the same speed as they do today, literally in ten years we can expect that computers will become 1000 times more powerful. Hard drives can store 10,000 times more information. It is likely that this breakthrough will not be associated with silicon chips, which are already reaching the limit of their capabilities.
Lessons from nature
In an attempt to build computers with molecular granularity, scientists are copying nature. Molecular assemblies are the main component for creating nanocomputers (biocomputers, molecular computers).
Currently, a “top-down approach” dominates in computer technology, which involves removing excess material from large objects. So, for example, lithography is used to create silicon microcircuits. But this technique does not reduce the electronic components to the size of an atom.
Therefore, in order to get faster and more powerful computers of tomorrow, scientists turned to the “bottom-up approach”. It is based on self-assembly of molecular structures. This idea was taken from nature, which uses various building blocks to create nucleic acid molecules.
The process of self-assembly of molecules will be due to the following conditions:
- thermodynamic factors (force of interaction of molecules);
- kinetic factors (assembly speed);
- forces holding the entire structure together.
History of the creation of molecular-based computers
Back in 1974, student Mark Ratner and his supervisor Arieh Aviram reported the possibility of miniaturization of electronic components to the size of a molecule. Aviram proposed a revolutionary idea for replacing silicon transistors and diodes with individual organic molecules.
At the same time, the starting point for such a scientific revolution, the “molecular rectifier”, was theoretically described. Based on the name, this device is designed to convert AC to DC.
However, the idea of Ratner and Aviram initially did not find proper support and sank into oblivion. Only a few years later, in the early 80s, a small group of scientists took up their work and began to implement them. At this time, molecular electronics was born.
Stages of development of molecular electronics
During its existence, the most significant breakthroughs in the field of molecular computers are characterized by three periods: 1974 (origin), 80s of the last century (resumption of research), early 2000s of the 21st century (a number of breakthroughs and inventions). In 2015, rapid growth in this area slowed down a bit, which does not allow us to say that in the near future silicon components will be replaced by molecular ones.
So what characteristics of molecular computers will allow new technologies to achieve? The answer to this question lies on the surface. First of all, this is a significant reduction in size, increased speed and memory expansion.
The essence of the revolution of Aviram and Ratner
The molecule is supposed to be considered as a semiconductor diode. One part of it acts as an electron donor and is an analog of the n-region of the diode. The second part acts as a receiver of electrons and corresponds to the p-region of the diode. When voltage is applied to the edges of the molecule, the electrons will begin to move from one end to the other. Applying a voltage with the opposite sign will impede the movement of electrons.
To prove their concept, American scientists have proposed a molecular rectifier model. It is a separate molecule, at one end of which an alternating current flows, and at the other - a constant current.
Despite the fact that this proposal was published in Time magazine, the scientific community showed little interest in it at that time. And only at the end of the 70s of the last century, the interest in this topic was shown by the chemist of the US Navy research laboratory Forest Carter.
Building computers using molecular technology
The basis of almost any electronic device these days is such a component as a transistor. Computer technology in the coming years will be aimed at reducing the size of this component.
The figure shows the use of a cluster of molecules to create a quantized and controlled flow of charges at room temperature.
The transistor has three sections - the base, collector and emitter. When current flows between the collector and the emitter, the transistor is open. The voltage applied to the base, in this case, exceeds a certain threshold value. When a voltage less than a threshold value is applied to it, the transistor closes.
When creating molecular devices, it is planned to use the same principles. Molecule-based devices, like silicon transistors, will have switching functions.
Logic Gate from IBM
The molecular logic gate consists of two naphthalocyanine molecules that are scanned with the tip of a low-temperature scanning tunneling microscope. When a voltage pulse passes from one end of the molecule to the other, two hydrogen atoms in adjacent molecules (shown in white in the center of the molecule) will change their position.
In this case, the whole molecule will switch from “on” to “off”. This device will be a logic gate - one of the main components of computer chips and a building block for molecular computers.
Scope of molecular components
Block ensembles have found their application in the creation of displays. Recent advances in molecular electronics include single-molecule light emitting diodes and carbon nanotube transistors coupled to silicon in a monolithic integrated circuit.
Scientists from the Hebrew University of Jerusalem have proposed the creation of molecular nanowires based on DNA. They will be an alternative to copper wires. At Columbia University of New York, they calculated the coefficient of rectification of a diode on a single molecule - it was more than 200 times.
Researchers at the University of Jyväskylä (Finland) have developed molecular computer memory. This type of memory can remember the direction of the magnetic field for an extended period of time after being turned off at extremely low temperatures. In the future, this discovery will increase the capacity of hard drives without increasing their size.
Computers of the future
Despite the fact that a number of breakthroughs have been made in the field of molecular electronics, a photo of a molecular computer on the Internet cannot be found. This is because the computer itself does not yet exist on such technology.
But in the near future we can expect the invention of molecular computers. They belong to von Neumann architecture, you can already be sure of this now. This is because molecules must replace electronic components, and the structure of the computer will remain unchanged.
Materials for Molecular Electronics
1. Polyacetylene.
2. Polyphenylene-vinylene.
3. Polypyrrole (X = NH) or polythiophene (X = S).
4. Polyaniline (X = NH / N) or polyphenylene sulfide (X = S).