Significant enhancement in GaAs HEMT thermal performance

Our colleagues from the department of III-V semiconductors IEE SAS,  Slovak University of Technology, and Wuhan University in China have achieved a significant advancement in high-electron-mobility transistor (HEMT) technology prepared from GaAs semiconductor. These devices, crucial for applications in space and defence technologies, high-frequency communication, or quantum computing, where compound-semiconductor amplifiers are widely used. Such amplifiers enable high-frequency low noise operation even at cryogenic temperatures, essential for high-fidelity amplification of weak qubit states. In this study we documented an enhancement of thermal transport properties of GaAs nanomembranes transferred from host GaAs substrate onto foreign ones (sapphire, Si, SiC) with various thermal conductivity. GaAs nanomembranes are used as a base ‚buffer‘ layer from which transistor is then fabricated. Epitaxial lift-off (ELO) technique was used to release the nanomembrane from the host substrate, which then adhered to the foreign substrates via van der Waals forces. Transient thermoreflectance (TTR), a nondestructive optical method was used for thermal characterisation of transferred nanomembranes and electrothermal simulation of a complete GaAs HEMT was prepared to verify the device improvement. The simulation was extended to also account for diamond substrates. Results from this calibrated physics-based simulation suggested a significant reduction in transistor self-heating and decrease in device thermal resistance (R_th) by approximately 30% when using SiC and diamond substrates. Additionally, simulations predict that optimizing the GaAs/substrate interface could further lower HEMT temperatures, in an ideal case by up to 29 – 41%. These resuls confirm the potential of the ELO technology as HEMT devices prepared from the transferred nanomembranes may offer higher power whilst maintaining their other parameters and without the risk of overheating. SiC substrates stand out as a cost-effective alternative to diamond, offering a balance between thermal performance and large-scale production feasibility. Moreover, use of the ELO process enables the reuse of GaAs substrates, significantly lowering production costs and improving sustainability of the fabrication process.

Learn more: https://pubs.acs.org/doi/10.1021/acsaelm.4c00659
Authors: Filip Gucmann, Biwei Meng, Aleš Chvála, Róbert Kúdela, Chao Yuan, Milan Ťapajna, Martin Florovič, Fridrich Egyenes, Peter Eliáš, Fedor Hrubišák, Jaroslav Kováč Jr., Ján Fedor, Dagmar Gregušová