Uniaxial stress tuning of interfacial thermal conductance in cubic BAs/4H-SiC heterostructures

Abstract

Understanding interfacial thermal transport is essential for improving thermal management in high-speed power electronic devices, where the efficient removal of excess heat is a critical challenge. In this study, a machine learning interatomic potential with near first-principles accuracy was employed to investigate the interfacial thermal conductance (ITC) between [111]-oriented cubic boron arsenide (cBAs) and [0001]-oriented 4H silicon carbide (4H-SiC), as well as its dependence on uniaxial stress. Among all possible bonding configurations at the cBAs(111)/4H-SiC(0001) interface, the B-C bonded interface was identified as the most energetically favorable. Non-equilibrium molecular dynamics simulations revealed that, under ambient conditions (300 K and 0 GPa), the ITC of the B-C interface reaches 353 $\pm$ 6 MW m$^{-2}$ K$^{-1}$, and increases monotonically to 460 $\pm$ 3 MW m$^{-2}$ K$^{-1}$ under a uniaxial stress of 25 GPa perpendicular to the interface. For comparison, the As-C bonded interface exhibits a lower ITC, increasing from 233 $\pm$ 7 to 318 $\pm$ 6 MW m$^{-2}$ K$^{-1}$ over the same stress range. These results demonstrate that proper interfacial bonding and moderate uniaxial stress can significantly enhance thermal transport across the cBAs(111)/4H-SiC(0001) heterointerface, offering valuable insight for thermal design in next-generation power electronics.

Figures (6)

• Figure 1: Regression evaluation of the NEP model and structures included in the training dataset. (a) Evolution of the total loss and individual loss components during NEP training. (b–d) Parity plots of NEP predictions versus DFT references for atomic energies, atomic forces, and virial stresses, respectively. Regression evaluation metrics including RMSE, mean absolute error (MAE), and R-squared (R$^2$) are presented in each panel. The corresponding data distributions are shown in the histograms above each subplot. Solid diagonal lines serve as visual guides. (e–f) Crystal structures of cBAs and 4H-SiC included in the dataset. (g–h) Interfacial structures featuring B–C bonding, shown from two different viewing angles, visualized using VESTA VESTA. In (g), the side lengths of the red dashed rectangle equal half of the in-plane lattice parameters of the corresponding heterostructure.
• Figure 2: (a) Schematic diagram of the interfacial model setup used for NEMD simulations; (b) Magnified view of the dashed-circle region at the interface in (a), illustrating the atomic configuration with B–C interfacial bonding; (c) Temperature profile across the interface at 300 K and 0 GPa obtained from the NEMD simulation. The model was divided into 50 slices along the transport direction, each with a thickness of approximately 10 Å, and the temperature of each slice was calculated to obtain the temperature profile. The black temperature points on both sides of the interface represent the reference points used to determine the actual temperature drop, $\Delta T$, in this study. The inset shows the cumulative energy exchanged by the thermostats coupled to the heat source and heat sink.
• Figure 3: Phonon spectra and EOS of cBAs and 4H-SiC. Panels (a–b) and (c–d) show the results for cBAs and 4H-SiC, respectively. In the phonon plots, red circles represent DFT results, while blue solid lines indicate NEP predictions. In the EOS plots, blue diamonds and yellow crosses denote NEP and DFT data points, respectively. The blue solid and yellow dashed curves are the Birch–Murnaghan fits to the NEP model and DFT data, respectively. Insets highlight the details near the equilibrium volume.
• Figure 4: Interfacial energetics of cBAs(111)/4H-SiC(0001) with different atomic bonding configurations. (a–d) Interfacial energy as a function of interlayer spacing for interfaces formed by B–C, B–Si, As–Si, and As–C bonding, respectively. Cross markers indicate DFT-calculated energies at the energy-favored interfacial distances predicted by NEP model. (e–h) Interfacial energy landscapes corresponding to lateral sliding at the equilibrium interlayer spacing for each bonding type, illustrating the relative stability and shear resistance of the interface configurations. The maximum interfacial energy encountered along the sliding path is taken as the reference zero for each sliding interface. The region labeled as $L\times \sqrt{3} L$ in (e–h) corresponds to the red dashed rectangle area in Fig. \ref{['nepandstructure']}(g), i.e. $L = \frac{\sqrt{3}}{2}\cdot3.40$ Å.
• Figure 5: (a) ITC $G$ as a function of applied stress for two bonding configurations (i.e., B–C and As–C bonding) at the cBAs(111)/4H-SiC(0001) interface, obtained from NEMD simulations at 300 K. Error bars represent the standard error from five independent simulations for each data point. (b) Spectral ITC at 300 K, 0 GPa for two type of interface. (c) and (d) Normalized PDOS spatially projected within 40 Å of the As–C and B–C interfaces, respectively. The dashed white line indicates the interface position. (e) and (f) represent the evolution of the PDOS under uniaxial stress for the constituent materials in the As–C and B–C interface models, respectively, calculated in regions on both sides of the interface with a thickness of 40 Å.