Thermal expansion coefficients of high thermal conducting BAs and BP materials

TL;DR

This study measures the thermal expansion coefficients of BAs and BP crystals, showing their compatibility with common semiconductors, which is crucial for thermal management in high power electronic devices.

Contribution

The paper provides the first detailed experimental measurements of CTE for BAs and BP over a wide temperature range, highlighting their suitability as heat spreader materials.

Findings

BAs CTE at room temperature is 3.6 ± 0.15 × 10E-6 /K.

BP CTE at room temperature is 3.2 ± 0.2 × 10E-6 /K.

Both materials have CTE values more compatible with semiconductors than diamond.

Abstract

Recent reported very high thermal conductivities in the cubic boron arsenide (BAs) and boron phosphide (BP) crystals could potentially provide a revolutionary solution in the thermal management of high power density devices. To fully facilitate such application, compatible coefficient of thermal expansion (CTE) between the heat spreader and device substrate, in order to minimize the thermal stress, need to be considered. Here we report our experimental CTE studies of BAs and BP in the temperature range from 100K to 1150K, through a combination of X-ray single crystal diffraction and neutron powder diffraction. We demonstrated the room temperature CTE, 3.6 $\pm$ 0.15 $\times$ 10E-6 /K for BAs and 3.2 $\pm$ 0.2 $\times$ 10E-6 /K for BP, are more compatible with most of the semiconductors including Si and GaAs, in comparison with diamond, and thus could be better candidates for the future heat spreader materials in power electronic devices.