Thermal Management in Multi-Finger GaN-on-Si HEMTs: Understanding and Mitigating Self-Heating and Thermal Crosstalk for Enhanced Device Reliability

GaN-based devices for RF and high-power applications use multi-finger configuration to achieve desired high output power. The self-heating effects and reliability of single-finger GaN transistors have been reported, however, a holistic understanding of thermal effects within commercially viable multi-finger configurations, as well as the ramifications of these dynamics on device reliability, is yet to be fully realized. In this work, we (i) examine the difference in the thermal mechanism between single-finger and multi-finger GaN-on-Si HEMTs by high-resolution thermoreflectance microscopy, (ii) find that the reliability degradation of multi-finger GaN-on-Si HEMTs diverges from their single-finger counterparts, (iii) uncover the reliability degradation mechanism specific to multi-finger GaN-on-Si HEMTs, (iv) propose and fabricate a novel non-uniform multi-finger configuration to solve the thermal crosstalk issue, (v) and prove the improved device reliability potential of the novel multi-finger configuration. The extensive insights into multi-finger devices, including thermal effects and novel reliability degradation mechanisms would help eradicate performance and reliability barriers caused by thermal effects in various power devices as well as GaN devices.