Optimization of central source contact length to mitigate temperature variation and thermal crosstalk in multi-finger AlGaN/GaN HEMTs: Reliability-based simulation

Thermal crosstalk and temperature variations among gate fingers hinder the operation of multi-finger AlGaN/GaN high-electron-mobility transistors (HEMTs) by increasing channel lattice temperatures and exacerbating the degradation of device performance. These thermal phenomena intensify channel temperature variations, further accelerating performance degradation and elevating failure rates in multi-finger HEMTs. Although self-heating effects in AlGaN/GaN HEMTs have been widely investigated, the thermal issues with multi-finger configurations, including thermal crosstalk and temperature non-uniformity, have not been extensively studied. This study investigates the thermal and DC characteristics of single-finger and multi-finger HEMTs to mitigate thermal crosstalk and inter-finger temperature variations. The design of a four-finger HEMT is optimized by adjusting the central source contact length to 6 μm, which increases the spacing between the second and third gate fingers to reduce thermal interaction and ensure uniform temperature distribution. The proposed configuration enhances the DC and thermal characteristics, delivering a more uniform temperature distribution among the fingers than the conventional structure, albeit at the expense of reduced area efficiency, which reveals a trade-off between performance and spatial utilization. Nevertheless, the optimized design improves the thermal stability and reliability of multi-finger HEMTs, addressing key concerns with AlGaN/GaN power devices.