As microchips shrink, maintaining efficient transmission of electrical signals between their components becomes increasingly difficult: electron scattering increases in ultrathin conductors, raising resistance and energy losses. Chinese scientists have synthesized a carbon material less than one nanometer wide that exhibits nearly ballistic electron transport. In the future, it could provide the basis for ultrathin electrical interconnects capable of operating with minimal losses.

According to Global Times, citing the Xinhua news agency, the material was developed by a team of scientists at the University of Science and Technology of China in Hefei. The findings were published in the journal Nature.

The newly developed material is a carbon pentaheptite nanoribbon. Its structure consists of carbon atoms joined into five- and seven-membered rings. Experiments showed that one of the resulting variants has metallic properties and allows electrons to move efficiently with relatively little scattering.

Nearly ballistic electron transport

The researchers produced two types of nanoribbons with similar basic structures but different arrangements of carbon chains along their edges. The first variant, designated CPHN 1, exhibited metallic behavior. The second, CPHN 2, proved to be a semiconductor with a narrow band gap.

Measurements showed that the electrical conductance of CPHN 1 approaches one conductance quantum—a fundamental unit of electrical conductance. The material also exhibits nearly ballistic electron transport: electrons move through its structure with minimal scattering.

This property is of particular interest for miniature electronics. When conductors become extremely thin, interactions between electrons and the material's boundaries and defects can increase scattering and raise resistance. As a result, signal transmission involves energy losses and heat generation.

If scientists can harness the new nanoribbon's properties in actual electronic devices, it could potentially enable more compact interconnects between microchip components and reduce losses during electrical signal transmission. The development could also have implications for future carbon electrodes and all-carbon electronics.

How the new material was produced

Carbon can form materials with entirely different characteristics depending on how its atoms are arranged and bonded. Diamond and graphite, for example, consist of the same chemical element but have different structures and physical properties. In graphene, carbon atoms form a hexagonal lattice.

As far back as 1996, theorists proposed that a structure made up of five- and seven-membered carbon rings could have metallic properties and conduct electricity. However, producing such a material in a controlled manner and experimentally confirming its characteristics remained elusive for many years.

A team led by Professors Wang Bing and Fan Qitang developed a step-by-step synthesis method on a silver surface. The scientists first used relatively stable molecules containing eight-membered carbon rings, which they linked into chains. When heated, the rings transformed into pairs of five-membered rings, forming polypentalene chains.

The temperature was then raised further. Adjacent chains joined side by side—a process the researchers compare to closing a zipper. Seven-membered rings formed between them, resulting in nanoribbons containing both types of carbon structures.

The work demonstrates that changing the arrangement of carbon rings in a structure less than one nanometer wide can produce materials with different electronic characteristics. This opens up new opportunities to study how atomic structure affects conductivity.

However, practical applications are still a long way off. Scientists will need to refine the synthesis process and determine whether the material can be integrated into actual electronic devices. For now, this remains an experimental development rather than a ready-made replacement for the conductors used in modern microchips.