Ultra-pure boron nitride yields high thermal conductivity twice that of copper

A team led by professor Martin Kuball of the University of Bristol’s Center for Device Thermography and Reliability (CDTR) in the UK has found that, by making an ultra-pure version of boron nitride, it was possible to demonstrate its high thermal conductivity potential for the first time, which at 550W/mk is twice that of copper, paving the way for safer and more efficient electronic devices including mobile phones, radars and even electric cars (‘Modulating the thermal conductivity in hexagonal boron nitride via controlled boron isotope concentration’, Communications Physics vol2, Article no: 43 (2019)).

“Most semiconductor electronics heat up when used. The hotter they get, the greater the rate at which they degrade, and their performance diminishes,” notes Kuball. “As we rely more and more upon our electronic devices, it becomes increasingly important to find materials with high thermal conductivity which can extract waste heat,” he adds.

“Boron nitride is one such material which was predicted to have a thermal conductivity of 550W/mK, twice that of copper. However, all measurements to date seemed to show its thermal conductivity was much lower [220–420WmK],” Kuball continues. “By making this material ‘ultra-pure’, we have been able to demonstrate for the first time its very high thermal conductivity potential.” Specifically, for monoisotopic 10B h-BN, an in-plane thermal conductivity as high as 585WmK is measured at room temperature, about 80% higher than that of h-BN with a disordered isotope concentration (52%:48% mixture of 10B and 11B).

Kuball says that the next step was to start making active electronic devices from boron nitride, as well as integrating it with other semiconductor materials.

“In demonstrating the potential of ultra-pure boron nitride, we now have a material that can be used in the near future to create high-performance, high-energy-efficiency electronics,” he adds. “Our reliance on electronics is only going to increase, along with our use of mobile phones and adoption of electric cars. Using more efficient materials, like boron nitride, to satisfy these demands will lead to better-performance mobile phone communication networks, safer transportation and ultimately, fewer power stations.”

Tags: hBN

Visit: www.nature.com/articles/s42005-019-0145-5

Visit: www.bristol.ac.uk/physics/people/martin-h-kuball/overview.html