For the first time, engineers were able to build a prototype of a processor using carbon nanotubes.The nanotubes have long been the star of so-called “promising technologies” to replace silicon in a new generation of faster processors with lower power consumption, and without the limitations of miniaturization of silicon.
The problem is that their properties have been demonstrated with unsurpassed individual nanotubes.Everything gets more complicated when trying to make them work in groups and in an orderly fashion.Not only is it difficult to align the nanotubes, as it is very problematic to separate metallic and semiconducting versions that inevitably come together in the production process.
Carbon nanotube transistor
The challenge now began to be surpassed by IBM scientists, who built a prototype chip with more than 10,000 transistors from carbon nanotubes.The prototype chip of carbon nanotubes opens a real prospect of replacement for silicon, which is approaching the limits of miniaturization – each carbon nanotube transistor can be formed by only a few hundred atoms.
The electrons move much more rapidly in carbon nanotubes than in the silicon, allowing higher speed data transmission and low heat dissipation.“The motivation for working with carbon nanotube transistors that are nanoscale in extremely small dimensions, they outnumber transistors made of any other material. Nevertheless, there are challenges to overcome, such as ultra high purity of carbon nanotubes and placement precise nanoscale. significant advances We both areas, “says Supratik Guha, coordinator of the team that created the prototype.
To overcome these barriers, researchers developed a new method based on ion exchange chemistry, which allows precise placement of controlled and aligned carbon nanotubes on a substrate.This allowed the controlled placement of individual nanotubes with a density of about one billion per square centimeter, more than 100 times greater than the best previous experiments.
The process begins with dipping the carbon nanotubes in a surfactant, a kind of soap which makes them soluble in water.The substrate is composed of two trenches constructed of oxides: hafnium oxide (HfO2) and silicon oxide (SiO2).
The substrate is immersed in the solution of carbon nanotubes, making these bind to the HfO2 through a chemical bond already aligned, while the rest of the surface remains clean.
Expansion of scale
The experimental chip was built using standard technologies in the semiconductor industry, which points to the possibility of a large-scale manufacturing.Using this technique, the IBM scientists built more than 10,000 nanotube transistors on a single chip.
The path to true carbon processors will work to expand the amount of nanotube transistors on each chip – a processor real need more than 1 billion transistors.