The Influence of Annealing Temperature on the Interfacial Heat Transfer in Pulsed Laser Deposition-Grown Ga2O3 on Diamond Composite Substrates

Abstract

As devices become more miniaturized and integrated, the heat flux density has increased, highlighting the issue of heat concentration, especially for low thermal conductivity gallium oxide (Ga2O3). This study utilizes diamond composite substrates with an AlN transition layer to assist Ga2O3 in rapid thermal dissipation. All samples were prepared using pulsed laser deposition (PLD) and annealed at 600–1000 °C. The microstructure, surface morphology, vacancy defects, and thermal characteristics of post-annealed Ga2O3 were then thoroughly investigated to determine the mechanism by which annealing temperature influences the heat transfer of heterostructures. The results demonstrate that increasing the annealing temperature can improve the crystallinity of Ga2O3 while also reducing oxygen vacancy defects from 20.6% to 9.9%. As the temperature rises to 1000 °C, the thermal conductivity of Ga2O3 reaches a maximum of 12.25 W/(m·K). However, the interface microstructure has no direct correlation with annealing temperature. At 700 °C, Ga2O3/diamond exhibits a maximum thermal boundary conductance of 127.06 MW/(m2·K). Higher temperatures (>800 °C) cause irregular mixtures to form near the heterointerface, intensifying phonon interface scattering and sharply deteriorating interfacial heat transfer. These findings contribute to a better understanding of the heterointerface thermal transfer influence mechanism and provide theoretical guidance for the thermal management design and physical analysis of Ga2O3-based power devices.