Leap in chip technology unveiled in joint study

Scientists in China and South Korea say they have made a breakthrough in the development of amorphous semiconductors, with a new method that could lead the way to a new generation of semiconductor chips.

Complementary metal-oxide semiconductor (CMOS) technology, widely used to make memory chips and computer processors, helps to produce reliable integrated circuits that require low inputs of power.

Traditional CMOS technology integrates polycrystalline semiconductors, which are made up of many crystallised silicon grains that all have their own structure.

Amorphous semiconductors, which lack this order and have randomly distributed atoms, are more cost-effective, simple and uniformly manufactured, according to the team of researchers.

However the traditional amorphous hydrogenated silicon used in such applications “falls short in electrical properties, necessitating the exploration of new materials”, they wrote in a paper published as an accelerated preview in peer-reviewed journal Nature last Wednesday. The paper has undergone peer review but requires further proofing.

Creating amorphous semiconductors with high electron mobility – the speed at which an electron can move through a semiconductor – “holds the promise of enhancing scalable CMOS technology and facilitating the integration of multifunctional electronics”, the paper says.

However, challenges to developing suitable amorphous semiconductors have held back the development of new generation devices.

The team from Chengdu’s University of Electronic Science and Technology of China and the Pohang University of Science and Technology in South Korea say they have devised a “pioneering design strategy for amorphous p-type semiconductors” that could make this possible.

The development of “thin-film transistors”, the technology that led to liquid crystal screen displays, had been propelled forward by the creation of high-mobility amorphous n-type semiconductors, the team said. Developing p-type semiconductors for CMOS had proved a major challenge, as the compounds used could only perform optimally in crystalline forms, they said.

Crystalline forms have “low stability, complex synthesis processes, large-area non-uniformity, and a lack of industrial compatibility”, compared to amorphous forms, according to their paper.

However, the team found a strategy to use thermal evaporation to create a tellurium-based composite that could allow a commercially viable amorphous p-type semiconductor to become a reality. Tellurium is an emerging semiconductor material.