  The ultra-wide bandgap, high breakdown electric field, and large-area
affordable substrates make \b{eta}-Ga2O3 promising for applications of
next-generation power electronics while its thermal conductivity is at least
one order of magnitude lower than other wide/ultrawide bandgap semiconductors.
To avoid the degradation of device performance and reliability induced by the
localized Joule-heating, aggressive thermal management strategies are
essential, especially for high-power high-frequency applications. This work
reports a scalable thermal management strategy to heterogeneously integrate
wafer-scale monocrystalline \b{eta}-Ga2O3 thin films on high thermal
conductivity SiC substrates by ion-cutting technique. The thermal boundary
conductance (TBC) of the \b{eta}-Ga2O3-SiC interfaces and thermal conductivity
of the \b{eta}-Ga2O3 thin films were measured by Time-domain Thermoreflectance
(TDTR) to evaluate the effects of interlayer thickness and thermal annealing.
Materials characterizations were performed to understand the mechanisms of
thermal transport in these structures. The results show that the
\b{eta}-Ga2O3-SiC TBC values increase with decreasing interlayer thickness and
the \b{eta}-Ga2O3 thermal conductivity increases more than twice after
annealing at 800 oC due to the removal of implantation-induced strain in the
films. A Callaway model is built to understand the measured thermal
conductivity. Small spot-to-spot variations of both TBC and Ga2O3 thermal
conductivity confirm the uniformity and high-quality of the bonding and
exfoliation. Our work paves the way for thermal management of power electronics
and \b{eta}-Ga2O3 related semiconductor devices.
