Boron Arsenide: A Breakthrough Thermal Substrate for High‑Power Electronics

Emerging substrates promise superior heat management compared to today’s leading materials in high‑power density devices.

Thermal management has rapidly become one of the most critical challenges for electrical engineers. As the power density of electronics climbs, so does the heat they generate. Maintaining reliable operation requires materials that can efficiently extract and dissipate this thermal energy, protecting sensitive components and sustaining peak performance.

Manufacturers of high‑power devices typically rely on diamond or silicon carbide substrates to channel heat away from power‑dense semiconductors such as transistors. Recent research has identified a new material that can pull heat from hot spots with markedly greater efficiency, potentially delivering tangible gains in device performance and energy savings.

What Superior Thermal Management Means for the Power Electronics Industry

As transistor dimensions shrink to the nanometer scale, manufacturers can pack more transistors onto a chip, boosting performance but also generating substantial heat. Without robust thermal management, these chips can overheat, throttle, and suffer reliability losses. Over time, thermal stress can even precipitate premature failure.

Industry analysts warn that the limits of Moore’s Law— the historic trend of doubling transistor count every two years—are tightening largely because of escalating heat‑management demands.

A thermal substrate that outperforms current state‑of‑the‑art materials could help the industry sustain the momentum of Moore’s Law, keeping processing power growth on track.

Boron Arsenide Emerges as a Promising Thermal Substrate for Semiconductors

In 2018, researchers from the University of California, Los Angeles (UCLA) and the Irvine Materials Research Institute, led by Associate Professor Yongjie Hu, produced defect‑free boron arsenide (BAs) in their laboratory. Their work demonstrated that BAs excels at drawing and dissipating heat compared to conventional semiconductor materials.

For the first time, the team integrated BAs directly into gallium nitride (GaN) high‑electron‑mobility transistors (HEMTs), the work of which was published in Nature Electronics in June 2021. The study showed that BAs substrates can outperform even the most advanced thermal materials in high‑power density settings.

More Effective Than Diamond or Silicon Carbide

To benchmark performance, the researchers compared GaN HEMTs built on BAs, diamond, and silicon carbide (SiC) substrates. At a power density of 15 W mm⁻¹, the BAs‑based HEMT’s temperature rose from ambient to 188 °F, whereas the diamond‑based device reached 278 °F and the SiC‑based device peaked near 332 °F.

These results indicate that BAs substrates enable devices to operate at higher power levels. The superior performance stems from BAs’s high thermal conductivity and exceptionally low thermal boundary resistance, which together facilitate rapid heat extraction.

BAs can achieve thermal conductivities up to 1,300 W m⁻¹ K⁻¹—still below diamond’s 2,300 W m⁻¹ K⁻¹—but its near‑zero boundary resistance gives it a decisive edge in cooling applications.

Although BAs contains arsenic, it becomes stable and non‑toxic when incorporated into compounds like boron arsenide, as noted by Dr. Bing Lv of the University of Texas at Dallas, who has also pioneered the synthesis of high‑purity BAs for use as a substrate.

Consequently, BAs is regarded as safe for high‑performance electronics, matching the safety profile of SiC and diamond. Moreover, BAs can be synthesized and processed at a lower cost, reducing barriers to industrial adoption.

Nevertheless, further research is required to fully characterize BAs’s electronic properties and confirm long‑term reliability before widespread implementation. If subsequent studies continue to validate these findings, boron arsenide could become a cornerstone material for next‑generation electronics.