Jumping the gap can make the electronics faster

According to an international team of engineers, a quasi-particle that travels along the interface of a metal and a dielectric material could be the solution to the problems posed by contraction of electronic components.

"Microelectronic chips are ubiquitous today," said Akhlesh Lakhtakia, professor at Evan Pugh University, and professor Charles Godfrey Binder in engineering and mechanical sciences at Penn State. "The delay time for signal propagation in the wire-to-metal interconnections, the electrical losses in the metals causing an increase in temperature and the crosstalk between neighboring interconnects resulting from miniaturization and densification limit the speed of these chips. "

These electronic components are found in our smartphones, tablets, computers and security systems. They are used in hospital equipment, defense facilities and our transportation infrastructure.

The researchers explored various ways to solve the problem of connecting various miniaturized components in a world of increasingly restricted circuits. While photonics, the use of light to carry information, is attractive because of its speed, this approach is problematic because waveguides for light are larger than current microelectronic circuits, making difficult connections.

A pulse-modulated SPP wave moving to the right, guided by the interface of a dielectric material (above) and a metal (below), suddenly encounters the replacement of the material dielectric by air. Most of the energy is transmitted to the air / metal interface, but some is reflected at the dielectric / metal interface. The video covers 120 femtoseconds.

The researchers report in a recent issue of Scientific reports that "the signal can travel long distances without significant loss of fidelity" and that "the signals can possibly be transferred by SPP waves over several tens of micrometers (of air) into microelectronic chips".

They also note that calculations indicate that SPP waves can transfer information around a concave corner, which is a common situation in microcircuits.

SPP is a group phenomenon. These quasi-particles move along the interface of a conductive metal and a dielectric – a non-conductive material that can withstand an electromagnetic field – and appear on a macroscopic scale under the form of a wave.

According to Lakhtakia, PSPs are what gives gold its particularly shimmering brilliance. A surface effect, under certain conditions, of electrons in the metal and polarized charges in the dielectric material can act together and form an SPP wave. This wave, guided by the interface of the two materials, can continue to propagate even if the wire has a break or if the metal dielectric interface ends abruptly. The SPP wave can travel in air for a few tens of micrometers or the equivalent of 600 transistors arranged end to end in a 14 nanometer technology chip.

In addition, SPP waves only move when they are close to the interface, so they do not produce crosstalk.

The problem of using SPP waves in circuit design is that, if researchers know experimentally that they exist, the theoretical foundations of the phenomenon are less defined. The Maxwell equations governing SPP waves cover a continuum of frequencies and are complicated.

"Instead of solving Maxwell's frequency-frequency equations, which is impractical and subject to debilitating computational errors, we took several snapshots of electromagnetic fields," Lakhtakia said.

These snapshots, linked together, become a movie that shows the propagation of the pulse-modulated SPP wave.

"We are studying difficult problems," Lakhtakia said. "We are studying problems that were intractable 10 years ago, and improved computer components have changed the way we think about these issues, but we still need more memory."