High thermal conductivity in wafer-scale cubic silicon carbide crystals

Abstract

High thermal conductivity electronic materials are critical components for high-performance electronic and photonic devices as both active functional materials and thermal management materials. We report an isotropic high thermal conductivity exceeding 500 W m−1K−1 at room temperature in high-quality wafer-scale cubic silicon carbide (3C-SiC) crystals, which is the second highest among large crystals (only surpassed by diamond). Furthermore, the corresponding 3C-SiC thin films are found to have record-high in-plane and cross-plane thermal conductivity, even higher than diamond thin films with equivalent thicknesses. Our results resolve a long-standing puzzle that the literature values of thermal conductivity for 3C-SiC are lower than the structurally more complex 6H-SiC. We show that the observed high thermal conductivity in this work arises from the high purity and high crystal quality of 3C-SiC crystals which avoids the exceptionally strong defect-phonon scatterings. Moreover, 3C-SiC is a SiC polytype which can be epitaxially grown on Si. We show that the measured 3C-SiC-Si thermal boundary conductance is among the highest for semiconductor interfaces. These findings provide insights for fundamental phonon transport mechanisms, and suggest that 3C-SiC is an excellent wide-bandgap semiconductor for applications of next-generation power electronics as both active components and substrates.

A Critical Review of Thermal Boundary Conductance across Wide and Ultrawide Bandgap Semiconductor Interfaces

“…In contrast, the hydrophobic bonding results in an interlayer with varying thicknesses of 0.2–2.5 nm and an improved TBC of 100–250 MW m –2 K –1 . Meanwhile, Cheng et al grew 3C-SiC crystals on Si substrates by low-temperature CVD. They reported a record high TBC among semiconductor interfaces, which is above 600 MW m –2 K –1 .…”

Enhanced far-field coherent thermal emission using mid-infrared bilayer metasurfaces

“…However, the aspect ratio required increases with the thermal conductivity of the solids, and therefore a much longer and thinner suspended nanostructure need to be fabricated, which is technically more challenging. In our experiment, we chose SiO 2 as a polar dielectric with a low thermal conductivity of ∼1.4 W m −1 K −1 ( cf ., Si 3 N 4 with 9 W m −1 K −1 , 43 SiC with 490 W m −1 K −1 44 and hBN with 751 W m −1 K −1 45 ). Also, importantly, amorphous SiO 2 should not exhibit size-dependent thermal conductivity for the dimensions of our samples, which are down to 100 nm owing to their short phonon mean free paths.…”

High Thermal Stability and Low Thermal Resistance of Large Area GaN/3C‐SiC/Diamond Junctions for Practical Device Processes

“…TDTR was an ultra‐fast laser‐based pump‐probe technique capable of assessing the thermal properties of both bulk and nanostructured materials. [ 34 ] The pump beam periodically heated the sample surface while the probe beam detected the temperature variation of the sample surface via thermoreflectance. The signal picked up by a photodetector and a Lock‐in amplifier was fitted with an analytical heat transfer solution of the sample structure to infer unknown parameters.…”

“…[ 33 ] This feature positions 3C‐SiC as an ideal solution for mitigating the challenges related to lattice mismatch during bonding processes, ultimately facilitating seamless integration of GaN and diamond materials. Furthermore, corresponding 3C‐SiC thin films have been reported to possess record‐high thermal conductivity [ 34 ] . The computation of interfacial thermal resistance by the phonon diffuse mismatch model indicated that the thermal boundary resistance for the 3C‐SiC/diamond interface is comparatively lower when compared to other diamond heterointerfaces.…”