Ultra-Thin Capacitors Made of Barium Titanate Could Dramatically Boost Electronic Efficiency

Lawrence Berkeley National Laboratory researchers, working with the Catalan Institute of Nanoscience and Nanotechnology and Intel as part of its Beyond Moore's Law initiative to find ways for the semiconductor industry to continue to deliver performance and efficiency gains for each generation, have developed a way to build ultra-thin capacitors, which they claim could help produce high-efficiency memory and logic parts for future electronics.

"We need to get to low-voltage operation, since that is what scales the energy," explains co-author Ramamoorthy Ramesh, a senior faculty scientist and professor of physics and materials science and engineering, of the inspiration behind the project. "This work demonstrated, for the first time, the switching field of the model material, BaTiO₃ with voltages lower than 100 mV, on a relevant platform."

That material, barium titanate, was discovered nearly a century ago and is already used to produce capacitors — but, the team explains, they're simply too large to deliver the low-power operation needed for future high-efficiency electronics. "We've known about BaTiO₃ for the better part of a century," explains project lead Lane Martin, faculty scientist and professor of materials science and engineering, "and we've known how to make thin films of this material for over 40 years. But until now, nobody could make a film that could get close to the structure or performance that could be achieved in bulk."

The process developed by the team, pulsed-laser deposition, offers precise thickness control with a dramatic drop in defect rate — and an overall layer thickness of just 25nm, or less than a thousandth the width of a human hair. Its performance, meanwhile, matched its bulkier predecessors.

"This is a good early victory in our pursuit of low-power electronics that go beyond what is possible with silicon-based electronics today," claims Martin. "Unlike our new devices, the capacitors used in chips today don’t hold their data unless you keep applying a voltage. If you could make each logic operation in a computer a million times more efficient, think how much energy you save. That’s why we're doing this."

The team's next step is to reduce the capacitor size still further, down the the single-digit nanometer measurements required for use in modern processors, and to work with Intel to build first-generation prototype chips featuring the technology.

A paper detailing the team's work has been published in the journal Nano Materials under closed-access terms.