Integration of Atomic Layer Epitaxy Crystalline Ga2O3 on Diamond for Thermal Management

TL;DR

This study explores integrating Ga2O3 with diamond substrates via atomic layer epitaxy to enhance thermal management in high-power electronic devices, focusing on interface bonding and thermal boundary conductance improvements.

Contribution

It demonstrates that strong interfacial bonds significantly increase thermal boundary conductance between Ga2O3 and diamond, offering a promising approach for heat dissipation in Ga2O3 electronics.

Findings

Ga2O3 films exhibit low thermal conductivity due to nanocrystalline structure.

Ga2O3-diamond interface TBC is about 10 times higher with strong bonding.

Interface chemistry influences interfacial thermal transport, with variations in TBC.

Abstract

Ga2O3 has attracted great attention for electronic device applications due to its ultra-wide bandgap, high breakdown electric field, and large-area affordable substrates grown from the melt. However, its thermal conductivity is significantly lower than that of other wide bandgap semiconductors, which will impact its ability to be used in high power density applications. Thermal management in Ga2O3 electronics will be the key for device reliability, especially for high power and high frequency devices. Similar to the method of cooling GaN-based high electron mobility transistors by integrating it with high thermal conductivity diamond substrates, this work studies the possibility of heterogeneous integration of Ga2O3 with diamond for thermal management of Ga2O3 devices. In this work, Ga2O3 was deposited onto single crystal diamond substrates by ALD and the thermal properties of ALD-Ga2O3 thin films and Ga2O3-diamond interfaces with different interface pretreatments were measured by TDTR. We observed very low thermal conductivity of these Ga2O3 thin films due to the extensive phonon grain boundary scattering resulting from the nanocrystalline nature of the Ga2O3 film. However, the measured thermal boundary conductance (TBC) of the Ga2O3-diamond interfaces are about 10 times larger than that of the Van der Waals bonded Ga2O3 diamond interfaces, which indicates the significant impact of interface bonding on TBC. Furthermore, the TBC of the Ga-rich and O-rich Ga2O3-diamond interfaces are about 20% smaller than that of the clean interface, indicating interface chemistry affects interfacial thermal transport. Overall, this study shows that a high TBC can be obtained from strong interfacial bonds across Ga2O3-diamond interfaces, providing a promising route to improving the heat dissipation from Ga2O3 devices.