Thermal Conductivity above 2000 W/m.K in Boron Arsenide by Nanosecond Transducer-less Time-Domain Thermoreflectance

TL;DR

This study reports that cubic boron arsenide exhibits thermal conductivity exceeding 2000 W/m.K at room temperature, surpassing previous experimental limits and matching diamond, enabled by high-quality crystals and a novel measurement technique.

Contribution

The paper introduces a nanosecond, transducer-less time-domain thermoreflectance method and demonstrates record-high thermal conductivity in c-BAs, challenging existing theoretical predictions.

Findings

Thermal conductivity exceeds 2000 W/m.K in c-BAs.

High crystal quality correlates with increased ppa.

Room-temperature ppa surpasses previous experimental values.

Abstract

Cubic boron arsenide (c-BAs) has been theoretically predicted to exhibit thermal conductivity \k{appa} comparable to that of diamond, yet experimental measurements have plateaued at ~1300W/mK. We report room-temperature \k{appa} exceeding 2000W/mK in c-BAs, on par with single-crystal diamond. This finding is enabled by high-quality single crystals and a newly developed nanosecond, transducer-less time-domain thermoreflectance technique that allows spatial mapping of \k{appa} without metal transducers. Thermal conductivity correlates with crystal quality, as evidenced by stronger photoluminescence and longer photoluminescence lifetimes. However, the observed nanosecond lifetimes remain shorter than expected for an indirect bandgap semiconductor, suggesting room for further crystal quality improvement and higher \k{appa}. These results challenge current theoretical models and highlight c-BAs as a promising material for next-generation electronics.