By Josh Perry, Editor
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Researchers at the University of Texas at Dallas, the University of Illinois at Urbana-Champaign, and the University of Houston (Texas) have created crystals of boron arsenide that have extremely high thermal conductivity, which could be used instead of silicon to create high-powered, small electronics.

Researchers at UT Dallas and their collaborators have created and characterized tiny crystals of boron arsenide that have high thermal conductivity. (UT Dallas)

According to a report from UT Dallas, researchers initially created boron arsenide crystals in 2015 but the thermal conductivity was only 200 W/mK, slightly higher than silicon. The researchers have now optimized the process to produce crystals that dissipate 1,000 W/mK, second only to diamond for bulk materials.

Scientists used chemical vapor transport to create the crystals. “The raw materials — the elements boron and arsenic — are placed in a chamber that is hot on one end and cold on the other,” the article explained. “Inside the chamber, another chemical transports the boron and arsenic from the hot end to the cooler end, where the elements combine to form crystals.”

By adjusting the raw materials, the temperature and pressure of the chamber, the tubing that was used and even how the equipment was cleaned, the UTD team created crystals with much higher thermal conductivity.

“The way heat is dissipated in boron arsenide and other crystals is linked to the vibrations of the material,” the article said. “As the crystal vibrates, the motion creates packets of energy called phonons, which can be thought of as quasiparticles carrying heat. The unique features of boron arsenide crystals — including the mass difference between the boron and arsenic atoms — contribute to the ability of the phonons to travel more efficiently away from the crystals.”

The research was recently published in Science. The abstract stated:

“The high density of heat generated in power electronics and optoelectronic devices is a critical bottleneck in their application. New, high thermally-conducting materials are needed to effectively dissipate heat and thereby enable enhanced performance of power controls, solid-state lighting, communication, and security systems.

“We report our experimental discovery of high thermal conductivity of 1000 ± 90 W/m/K at room temperature in cubic boron arsenide (BAs) grown through modified chemical vapor transport technique. Such thermal conductivity is a factor of 3 higher than that of silicon carbide and surpassed only by diamond and the basal plane value of graphite.

“This work establishes BAs as the first realization of a new class of ultrahigh thermal conductivity materials predicted by a recent theory, and a potential revolutionary thermal management material.”