Scientists develop ultra-powerful microcapacitors for next-gen electronic devices

Microcapacitors made with engineered hafnium oxide/zirconium oxide films in 3D trench capacitor structures—the same structures used in modern microelectronics—achieve record-high energy storage and power density, paving the way for on-chip energy storage. Credit: Nirmaan Shanker/Suraj Cheema.

Researchers at Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley are making strides in the world of electronic devices by developing microcapacitors that could dramatically enhance how energy is stored and delivered right on microchips.

Their research, which could revolutionize the efficiency and size of electronic gadgets, has been published in the prestigious journal Nature.

Traditionally, electronic devices face energy loss when power travels between components.

To address this, scientists are working to integrate energy storage directly onto microchips, minimizing energy loss and maximizing efficiency.

However, achieving this requires the ability to store a lot of energy in a tiny space and deliver it quickly when needed—something past technologies haven’t been able to accomplish.

The team at Berkeley has found a promising solution using engineered thin films made from hafnium oxide and zirconium oxide—materials already commonly used in chip manufacturing. By tweaking these materials, they’ve managed to create microcapacitors with the highest energy and power densities ever reported.

Capacitors are fundamental components in electrical circuits, known for their ability to quickly deliver bursts of energy. Unlike batteries that store energy chemically, capacitors store energy in an electric field between two metallic plates separated by a dielectric material.

While they can release energy rapidly and endure many charge-discharge cycles without wearing out, traditional capacitors can’t hold as much energy as batteries, especially when shrunk to micro sizes.

The breakthrough came when the researchers utilized a phenomenon called “negative capacitance” in their microcapacitors.

This effect occurs when specific materials are layered together, resulting in a greater ability to store charge. Essentially, this method allows the microcapacitors to hold and deliver much more energy than typical capacitors of the same size.

The microcapacitors are constructed using a sophisticated technique called atomic layer deposition, allowing for precise control over the thickness and composition of the films.

By carefully balancing the ratio of hafnium oxide to zirconium oxide, the researchers could tweak the materials’ properties, switching between ferroelectric (having a natural electric polarization) and antiferroelectric states (which can be polarized under an electric field).

This careful manipulation at the microscopic level enables the capacitors to store an impressive amount of energy.

For instance, when the film composition is just right, the structure sits on the brink between ferroelectric and antiferroelectric states, creating a delicate balance that results in the negative capacitance effect. This means that even a small electric field can cause a significant increase in stored charge.

Collaborating with experts from MIT Lincoln Laboratory, the team then integrated these films into sophisticated three-dimensional structures within microchips, greatly enhancing the energy storage capacity without increasing the chip’s size.

The performance of these new microcapacitors is groundbreaking—they offer nine times the energy density and 170 times the power density of the best existing electrostatic capacitors. This means they can store much more energy and deliver it much faster than previous technologies.

These advancements could be crucial for powering future generations of small, energy-efficient devices across various applications, including Internet-of-Things sensors, edge computing systems, and more.

The researchers are now focusing on further improving these materials and scaling up their technology to integrate it into full-sized microchips, potentially ushering in a new era of compact, high-performance electronics.

Source: Lawrence Berkeley National Laboratory.