New technique to integrate 'novel' materials onto silicon will enable next-gen smart devices, claim researchers

Researchers at North Carolina State University claim breakthrough in integrating 'novel' materials onto silicon

Researchers from North Carolina State University and the US Army Research Office claim to have developed a technique to integrate different 'novel' materials onto silicon chips that can provide added capabilities.

These include multi-ferroic materials have both ferro-electric and ferro-magnetic properties; as well as topological insulators, which act as insulators in bulk, but have conductive properties on their surface; and, novel ferro-electric materials.

The researchers claim that the materials will enable the creation of new smart devices, sensors, non-volatile computer memory and micro-electromechanical systems (MEMS).

"These novel oxides are normally grown on materials that are not compatible with computing devices," said Jay Narayan, professor of Materials Science and Engineering at North Carolina State University. "We are now able to integrate these materials onto a silicon chip, allowing us to incorporate their functions into electronic devices."

The approach developed by the researchers enabled them to integrate the materials onto two platforms, both of which are compatible with silicon: a titanium nitride platform, for use with nitride-based electronics; and yttria-stabilised zirconia, for use with oxide-based electronics.

The researchers developed a suite of thin films that serve as a buffer, connecting the silicon chip to the relevant novel materials. The exact combination of thin films can vary depending on the novel materials being used.

For example, with multi-ferroic materials, the researchers used a combination of four different thin films: titanium nitride, magnesium oxide, strontium oxide and lanthanum strontium manganese oxide. But for topological insulators, they used a combination of only two thin films: magnesium oxide and titanium nitride.

These thin film buffers align with the planes of the crystalline structure in the novel oxide materials, as well as with the planes of the underlying substrate, effectively serving as a communicating layer between the materials.

This approach, called thin-film epitaxy, was first proposed by Narayan in a 2003 research paper - and has now been achieved.

"Integrating these novel materials onto silicon chips makes many things possible," said Narayan. "For example, this allows us to sense or collect data, to manipulate that data, and to calculate a response - all on one compact chip. This makes for faster, more efficient, lighter devices."

Another possible application, added Narayan, is the creation of LEDs on silicon chips, to make 'smart lights'. Currently, LEDs are made using sapphire substrates, which aren't directly compatible with computing devices. "We've already patented this integration technology, and are currently looking for industry partners to license it," said Narayan.