2D materials Enhance Thermal Conductance at van der Waals Interfaces of β-Ga₂O₃

Wide bandgap semiconductors have enabled the advancement of next-generation power electronics. Among them, β-Ga₂O₃ has attracted enormous interest because it can withstand higher voltages with higher efficiencies and can be fabricated using relatively low-cost melt-growth techniques. However, its low thermal conductivity causes thermal management challenges. One way to ensure efficient heat flow is to transfer a thin film of β-Ga₂O₃ onto a substrate that has high thermal conductivity. However, low thermal boundary conductance (TBC) at the interface is bottleneck for heat removal via the substrate. In this study, we investigate the possibility of improving TBC of β-Ga₂O₃/2D/3D interfaces using 2D material interlayers. We employed numerical models using first-principles phonon dispersion data and our new van der Waals-based AMM model that incorporates full phonon dispersions. Our study shows that the large overlap between the phDOS of β-Ga₂O₃ and that of 2D materials can be utilized to enhance TBC of β-Ga₂O₃/3D interfaces. However, if the interface roughness is very steep, TBC drops due to partial delamination of the 2D material, which reduces phonon coupling. Therefore, our study provides valuable insights into optimizing TBC of β-Ga₂O₃/3D interfaces, which will contribute to improving thermal management in electronic devices made of β-Ga₂O₃.