Improved Thermal Performance of InGaAs/GaAs Nanomembrane HEMTs Transferred onto Various Substrates by Epitaxial Lift-Off

High-frequency wireless communication in consumer, defense, and space applications heavily relies on the use of compound semiconductor amplifiers. Typically, the X to Ka wireless bands (similar to 8-40 GHz) are covered by GaN and GaAs-based devices, respectively, to the desired output power. GaAs-based high-electron mobility transistors (HEMTs) provide an unprecedented ultralow-noise high-frequency operation even at cryogenic temperatures, critically important for the high-fidelity amplification of weak qubit states in quantum computing. Increased output power from GaAs-based devices while maintaining low self-heating is an important but challenging objective. In this study, we used an epitaxial lift-off (ELO) technique to transfer GaAs nanomembranes onto foreign substrates (sapphire, Si, and SiC) and analyzed the thermal properties of the van der Waals-bonded GaAs films by nanosecond transient thermoreflectance (TTR). Electrothermal simulation of a GaAs HEMT was used to predict the thermal performance of the transferred devices, and a significant decrease of similar to 30% in the device thermal resistance (Rth) was observed when SiC and diamond substrates were used. Our results also predict that the on-state channel temperature rise can be further decreased by similar to 29 to 41% if the GaAs/substrate interface is improved by increased thermal boundary conductance. Our study finds that the ELO-transferred GaAs HEMTs onto foreign highly thermally conductive substrates can significantly improve their thermal performance and allow for higher output while keeping the on-state temperature within the safe operating margin.