Novel materials could cool high-power devices -

Novel materials could cool high-power devices

New substrates could be more effective than state-of-the-art thermal management materials in high-power density applications.

Thermal management has quickly become one of the most significant problems facing electrical engineers. As the power density of electronics has increased, so has the amount of thermal energy they generate. High performance requires materials that can draw in and dissipate this heat, preventing damage to sensitive electronic components and ensuring they operate efficiently.

Typically, manufacturers of electronics with high power density use substrates like diamond or silicon carbide to manage heat generated by semiconductors like transistors. Now, researchers have discovered a new material that draws heat from hot spots much more effectively. In practice, this material could help electronics manufacturers secure noticeable improvements in device performance and energy efficiency. It may ensure the continued development of faster and cheaper electronic devices.

What Better Thermal Management Means for the Power Electronics Industry

In shrinking transistor geometries down to nanometer scales, manufacturers can offer chips with high transistor density that enhance performance but also generate significant amounts of heat. Without some kind of thermal management system, these computer chips will overheat, slow down and become less reliable. Thermal stress can also damage them over time, resulting in premature failure.

Electronics industry observers have suggested that the industry should prepare for the end of Moore’s Lawthe tendency for transistor count to double every two years. That’s primarily due to the growing challenge heat management poses for electronic engineers.

A thermal substrate that offers performance much better than cutting-edge materials could ensure the electronics industry keeps pace with the theoretical Moore’s Law gains — continuing the growth in processing power we’ve come to expect over the past few decades.

Boron Arsenide Emerges as Potential Thermal Substrate for Semiconductors

In 2018, researchers from the University of California Los Angeles (UCLA) and Irvine Materials Research Institute, led by Associate Professor Yongjie Hu, developed defect-free boron arsenide (BA) in their laboratory. Their findings determined it was much more effective than conventional semiconductor materials in drawing and dissipating heat.

Now, for the first time, the research team has shown the practical effectiveness of BA by integrating it directly into cutting-edge, high-power gallium nitride (GaN)-based high electron-mobility transistors (HEMTs). The team’s findings, published in June 2021 in Nature Electronics, demonstrated how these substrates can be more effective than state-of-the-art thermal management materials in high-power density applications.

More Effective Than Diamond or Silicon Carbide

To evaluate the thermal management performance of GaN HEMTs with BAs, the research team compared these structures to GaN HEMTs with two conventional thermal substrates, diamond and silicon carbide (SiC).

At a power density of 15 watts per millimeter, the GaN HEMT with a boron arsenide substrate saw maximum heat increase from room temperature up to 188 F. The GaN HEMT with diamond saw escalations of up to 278 F, and the HEMT with a silicon carbide substrate both saw growth up to around 332 F.

According to the team, the results demonstrate that devices with a BAs substrate can sustain much higher operating power than those with conventional substrates. The researchers attributed the improved performance of the BAs substrate to the material’s high thermal conductivity and low thermal boundary resistance. The lower the resistance of a material, the more readily it will draw in and dissipate heat — helping to improve thermal management abilities.

The thermal conductivity of BAs can reach as high as 1,300 watts per meter-kelvin (W/(m·K)), compared to the approximately 2,300 W/(m·K) offered by diamond. Higher thermal conductivity is better, but an extremely low thermal boundary resistance means the material can provide better performance in cooling semiconductors.

Although BAs contain arsenic, arsenic becomes stable and nontoxic when incorporated into compounds like boron arsenide, according to Dr. Bing Lv. Lv is a University of Texas at Dallas-based physics professor and researcher who has also explored the potential of boron arsenide for thermal management and headed one of the first research groups to synthesize boron arsenide pure enough to use as a substrate.

As a result, BAs are considered as safe to use as silicon carbide or diamond in high-performance electronics. Furthermore, BAs can also be synthesized and processed relatively cheaply, so manufacturing cost shouldn’t be a barrier to the material’s adoption.

Even so, more research will be necessary. Before engineers can commit to a novel material like BAs, they must fully understand the material’s electronic properties and ensure they perform up to spec. Still, it’s likely that if research continues to demonstrate the effectiveness of the material, boron arsenide could have a major impact on electronics in the near future.

Emily Newton is a technology and industrial journalist who enjoys discovering how the IoT is impacting different industries. Emily is editor in chief of Revolutionized – an online magazine exploring trends in science, technology and industry. Subscribe to her newsletter to keep up with the latest.

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