Increased thermal conductivity of β-Ga2O3 using Al substitution: Full spectrum phonon engineering

Abstract

Improving the thermal conductivity of β-Ga2O3 is critical for optimizing its performance in high-power electronic devices, as effective thermal management significantly influences their output power and reliability. In this work, the thermal conductivities of β-Ga2O3 and (AlxGa1−x)2O3 alloys along the ( 2 ¯ 0 1) direction were first computed using a non-equilibrium molecular dynamics method based on the deep learning potential. Our results indicate that the calculated thermal conductivity of β-Ga2O3 is 16.6 W m−1K−1 along the ( 2 ¯ 0 1) direction, which is in excellent agreement with experimental measurements. In our findings, an Al to Ga ratio of 1:1 leads to the thermal conductivity of the (AlxGa1−x)2O3 alloy being more than twice that of β-Ga2O3, regardless of the Al substitution sites. The (Al0.5Ga0.5)2O3 alloy exhibits enhanced thermal conductivity due to the improved transport properties of optical phonon modes, including the increased group velocities, the enhanced participation, and the induced new vibrational modes at higher frequencies. This research provides theoretical predictions regarding the optimal Al to Ga ratio to enhance the thermal conductivity of (AlxGa1−x)2O3 alloys, offering crucial insights for the design and thermal management of β-Ga2O3 power devices.