Strong Temperature Dependence of Thermal Conductivity in High-Purity Cubic Boron Arsenide

Abstract

Materials with high thermal conductivity are needed to conduct heat away from hot spots in high power electronics and optoelectronic devices. Cubic boron arsenide (c-BAs) has a high thermal conductivity due to its special phonon dispersion relation. Previous experimental studies of c-BAs report a room-temperature thermal conductivity between 1000 and 1300 W m-1 K-1. We synthesized high purity isotopically enriched c-BAs single crystals with room-temperature thermal conductivity of around 1500 W m-1 K-1. Using time-domain thermoreflectance (TDTR), we measured thermal conductivity and found a 1/T2 temperature dependence between 300 K and 600 K - slightly stronger than predictions from state-of-the-art theoretical models. Brillouin and Raman scattering revealed minimal changes in phonon frequencies over the same temperature range, suggesting that the observed 1/T2 dependence is not caused by temperature dependent changes in phonon dispersion. To probe defect densities in the BAs crystals we studied, we conducted transient reflectivity microscopy (TRM) measurements of absorption at sub-bandgap photon energies. We observe a correlation between TRM signal intensity and thermal conductivity. Notably, samples with thermal conductivity near 1500 W m-1 K-1 still exhibited nonzero TRM signals, suggesting the presence of defects despite the high thermal conductivity.

arXiv comment31 pages, 10 figures

References in corpus (16)

• Tutorial: Time-domain thermoreflectance (TDTR) for thermal property characterization of bulk and thin film materials
• Four-phonon scattering diminishes the optical phonon contribution and isotope effect to thermal conductivity of III-V semiconductors
• Idealizing Tauc Plot for Accurate Bandgap Determination of Semiconductor with UV-Vis: A Case Study for Cubic Boron Arsenide
• Phonon-Phonon Interactions in Strongly Bonded Solids: Selection Rules and Higher-Order Processes
• Simultaneously high electron and hole mobilities in cubic boron-V compounds: BP, BAs and BSb
• Basic Physical Properties of Cubic Boron Arsenide
• Band structure and carrier effective masses of boron arsenide: effects of quasiparticle and spin-orbit coupling corrections
• A new elliptical-beam method based on time-domain thermoreflectance (TDTR) to measure the in-plane anisotropic thermal conductivity and its comparison with the beam-offset method
• Point defects and dopants of boron arsenide from first-principles calculations: donor compensation and doping asymmetry
• Optical properties of cubic boron arsenide
• Experimental demonstration of a generalized Fourier's Law for non-diffusive thermal transport
• Thermal expansion coefficient and lattice anharmonicity of cubic boron arsenide
• Photoluminescence mapping and time-domain thermo-photoluminescence for rapid imaging and measurement of thermal conductivity of boron arsenide
• Boron isotope effect on the thermal conductivity of boron arsenide single crystals
• Thermal Conductivity of BAs under Pressure
• Effect of isotope disorder on the Raman spectra of cubic boron arsenide