Scientists unlock the hidden power within silicon making electronics smaller, faster, and more efficient

Researchers at the University of California, Riverside have unlocked a hidden power within silicon, the backbone of modern electronics. Their findings could transform how future devices are built, making them smaller, faster, and more efficient.

At its core, silicon seems simple. It’s the second most common element in Earth’s crust and shapes every computer chip and phone. But deep down, it holds secrets. When studied at the tiniest scale, silicon reveals a world where electrons don’t just act like tiny balls. They also behave like waves. This wave behavior, called quantum interference, can turn electrical conductivity on or off like a switch.

At the quantum scale, scientists no longer think of electrons as just particles moving through a wire. Instead, they see them as waves that can cancel each other out, similar to noise-canceling headphones. Professor Tim Su from UC Riverside led the research. He explains, “We found that when tiny silicon structures are shaped with high symmetry, they can cancel out electron flow like noise-canceling headphones. What’s exciting is that we can control it.”

Their study, published in Journal of the American Chemical Society, shows that changing the symmetry of silicon molecules creates or suppresses a special effect called destructive interference. This interference can block electron flow completely, acting as a molecular-scale switch.

For decades, the tech world has carved ever-smaller circuits into silicon wafers. Engineers also used doping, which involves adding other elements to control conductivity. These methods fueled progress, but limits are near. At very small scales, unpredictable quantum effects start to appear. Electrons begin to tunnel through insulating barriers, creating leaks that slow down devices and waste energy.

Instead of carving silicon down, Su’s team built silicon structures from scratch, atom by atom. This “bottom-up” approach gave them perfect control over the molecule’s shape. More importantly, it let them guide how electrons move through these structures.

“Our work shows how molecular symmetry in silicon leads to interference effects that control how electrons move through it,” Su said. “And we can switch that interference on or off by controlling how electrodes align with our molecule.”

The scientists focused on a special form of silicon called sila-adamantane. First isolated in 2005, this molecule has a structure identical to a unit cell in crystalline silicon. It represents the smallest possible chunk of the silicon crystal. By studying it, researchers hoped to understand how quantum interference works at an atomic level.

They compared sila-adamantane to two other silicon structures: a bicyclic cluster called Si[3.3.1] and a simple linear chain called Si3. Using scanning tunneling microscopy break-junction (STM-BJ) measurements, they observed how each structure conducted electricity.

The results were striking. Conductance in sila-adamantane was 2.7 times lower than in the Si[3.3.1] cluster. The only difference was a single dimethylsilylene bridge in sila-adamantane, which enforced high symmetry in the molecule.

Why did this bridge matter so much? Density functional theory calculations showed that the dimethylsilylene unit forced the molecule into a shape with C3 symmetry. This meant that electrodes connected equally to each of the three bridge paths within the molecule. Depending on how these electrodes aligned, strong destructive quantum interference occurred, blocking electron flow almost completely.

In simpler terms, by tweaking the molecule’s shape, scientists could control whether electrons flowed through it or not. This control could create molecular switches with on/off ratios far higher than existing designs.

“This gives us a fundamentally new way to think about switching and charge transport,” Su said. “It’s not just a tweak. It’s a rethink of what silicon can do.”

The implications reach far beyond creating smaller transistors. Quantum interference effects could help build thermoelectric devices that turn waste heat into electricity, improving energy efficiency. They could also contribute to quantum computing, which uses quantum states like interference to perform calculations far faster than traditional computers.

In today’s field-effect transistors, quantum tunneling is usually seen as a problem. Electrons leak between parts of the circuit, causing energy loss. But quantum computers turn this issue into an advantage by using tunneling to store and manipulate information.

By understanding how tunneling works in molecules like sila-adamantane, engineers can design new devices that harness quantum behavior rather than fight it.

Previous studies of silicon focused on polysilanes, which are simple silicon chains. These studies showed that silicon-silicon bonds conduct better than carbon-carbon bonds, mirroring trends seen in larger silicon and carbon materials. However, when scientists tested more complex multicyclic silicon clusters, they discovered these acted like constrained linear systems. The branching paths in these clusters didn’t seem to affect conductivity much.

But sila-adamantane broke this pattern. Unlike previous clusters, it matched the exact structure of crystalline silicon. Tests showed that its symmetry caused destructive quantum interference, lowering its conductance dramatically compared to simpler structures.

The study also reveals that symmetry is not just a design feature – it’s a tool. By adjusting molecular symmetry, scientists can tune electronic properties precisely. This approach could lead to devices that use quantum effects for faster processing, lower power consumption, and new types of computing.

This breakthrough opens a new field of molecular electronics. Engineers could create ultra-small switches that operate based on quantum effects, not just physical connections. This method avoids the limits of traditional chip design, where circuits can’t get much smaller without problems.

“This represents the first example of dynamic modulation of destructive sigma quantum interference,” Su said. “And it enables us to achieve switching ratios higher than previously reported.”

While the work is still at the molecular research stage, its potential is vast. Quantum switches made from silicon could integrate easily into existing manufacturing processes. They could pave the way for devices that are not only smaller and faster but also smarter in how they manage energy and process information.

Understanding silicon’s behavior at the smallest scale changes everything. As Su and his team continue exploring, they could redefine the future of electronics, pushing the limits of what your phone, computer, or smartwatch can do.

Note: The article above provided above by The Brighter Side of News.

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