Superior interfacial thermal conductance between β -Ga2O3 and diamond realized through metal-assisted epitaxial strategy

ABSTRACT β-Ga2O3 exhibits great potential for next-generation power electronics, while its low thermal conductivity poses a challenge to efficient heat dissipation. We address this challenge by developing a gallium-assisted epitaxial strategy to synthesize highly oriented β-Ga2O3 film on diamond. The β-Ga2O3 presents a high thermal conductivity of 9.0 W m−1 K−1 and low thermal boundary resistance of 6.05 m2 K GW−1. In-situ experiments reveal a high interfacial bonding strength (>2.09 GPa), resulting from the atomically sharp and covalently bonded interface. The identified new interfacial phonon mode at ∼60 meV through the vibrational electron energy-loss spectroscopy can significantly enhance the phonon transport between diamond and β-Ga2O3. The developed gallium-assisted strategy may mitigate the thermal constraints of β-Ga2O3, offering a promising route for the heterointegration of β-Ga2O3-based power devices with diamond.