A neuroevolution potential for predicting the thermal conductivity of α, β, and ε-Ga2O3

Ga2O3 is an ultrawide-bandgap semiconductor with a variety of crystal configurations, which has the potential for a variety of applications, especially in power electronics and ultraviolet optoelectronics. However, there has been no single interatomic potential reported for Ga2O3 polymorphs in terms of molecular dynamics prediction of thermal conductivity. Here, one interatomic potential has been developed based on neural networks, which has the clear advantages of consuming less computational power than density functional theory and has high accuracy in predicting the thermal conductivity of the three polymorphs of Ga2O3. Using the neuroevolution potential, the thermal conductivity values at 300 K have been predicted. Hence, the kappa([average-)(alpha)(]) was 67.2% that of beta-Ga2O3, and the kappa([average-)(epsilon)(]) was only 26.4% that of beta-Ga2O3. The possible reasons for the discrepancies in thermal conductivity values in various crystal types and orientations have been explored. As a result, it could be shown that the contribution of low-frequency phonons to thermal conductivity was very significant in Ga2O3, and a unit cell with low symmetry and high atomic number would negatively impact the thermal conductivity of the material. In this work, a scheme has been proposed for accurately predicting the thermal conductivity of Ga2O3 and a relatively accurate value of the thermal conductivity of epsilon-Ga2O3 has been achieved, which could also provide an atomic-scale perspective for the insight into the thermal conductivity differences among alpha, beta, and epsilon-Ga2O3.

Automated summary

Ga2O3 is a semiconductor with a wide range of crystal configurations that holds potential for various applications, particularly in power electronics and ultraviolet optoelectronics. A new interatomic potential based on neural networks has been developed for Ga2O3, offering the advantages of lower computational requirements compared to density functional theory while maintaining high accuracy in predicting the thermal conductivity of Ga2O3 polymorphs. It has been discovered that low-frequency phonons significantly contribute to thermal conductivity in Ga2O3, and factors such as low symmetry and high atomic number can negatively impact the material's thermal conductivity. This study proposes a scheme for accurately predicting Ga2O3's thermal conductivity and successfully achieves relatively accurate results for epsilon-Ga2O3, providing an atomic-scale perspective on the differences in thermal conductivity among alpha, beta, and epsilon-Ga2O3.