Quasi-particles known as surface-plasmon-polariton (SPP) waves that travel along the interface between a metal and a dielectric material may be the solution to problems caused by shrinking electronic components, according to an international team of engineers.

"Microelectronic chips are ubiquitous today," said Akhlesh Lakhtakia, professor of engineering science and mechanics at Penn State. "Delay time for signal propagation in metal-wire interconnects, electrical loss in metals leading to temperature rise, and cross-talk between neighboring interconnects arising from miniaturization and densification limits the speed of these chips."

Researchers have explored a variety of ways to solve the problem of connecting various miniaturized components in a world of ever-shrinking circuits. While photonics – the use of light to transport information – is attractive because of its speed, this approach is problematic because the waveguides for light are bigger than current microelectronic circuits, which makes forming connections between them difficult.

Now, in a paper in Scientific Reports, the engineers report that "signals can possibly be transferred by SPP waves over several tens of micrometers (of air) in microelectronic chips" and "The signal can travel long distances without significant loss of fidelity". They also note that their calculations indicate that SPP waves can transfer information around a concave corner – a situation, along with air gaps, that is common in microcircuitry.

SPPs are a group phenomenon. These quasi-particles travel along the interface between a conducting metal and a dielectric – a non-conducting material that can support an electromagnetic field – and on a macroscopic level appear as a wave.

According to Lakhtakia, SPPs are what give gold its characteristic shimmery shine. Under certain conditions, electrons in the metal and polarized charges in the dielectric material can act together to form an SPP wave. Guided by the interface between the two materials, this wave can continue propagating even if a metal wire has a break in it or the metal-dielectric interface terminates abruptly.

The SPP waves can travel in air for a few tens of micrometers, or the equivalent of 600 14nm-wide transistors laid end-to-end. But they can only travel when in close proximity to the interface between the materials, so they do not produce crosstalk.

The problem with using SPP waves when designing circuits is that while researchers know experimentally that they exist, the theoretical underpinnings of the phenomenon are less defined. The Maxwell equations that govern SPP waves cover a range of frequencies and are complicated.

"Instead of solving the Maxwell equations frequency-by-frequency, which is impractical and prone to debilitating computational errors, we took multiple snapshots of the electromagnetic fields," explained Lakhtakia. These snapshots, strung together, become a movie that shows the propagation of the pulse-modulated SPP wave.

"We are studying tough problems," he added. "We are studying problems that were unsolvable 10 years ago. Improved computational components changed our way of thinking about these problems, but we still need more memory."

This story is adapted from material from Penn State, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.