Thermal Management of AlGaN/GaN Metal–Insulator–Semiconductor High‐Electron‐Mobility Transistor by AlN Buffer Engineering for Smart Power Chip Technologies

Thermal management remains a critical challenge in AlGaN/GaN metal–insulator–semiconductor high‐electron‐mobility transistors (MISHEMTs), particularly under high‐power operation where self‐heating degrades performance and reliability. This work proposes an AlN buffer‐engineered (AlN‐BE) MISHEMT to enhance breakdown voltage and electrothermal performance for smart power chip technologies. The device integrates an optimized AlN layer within the buffer to improve heat dissipation and electric‐field distribution without perturbing channel electrostatics. The AlN‐BE and conventional MISHEMTs exhibit nearly identical threshold voltages (−13.6 V) and comparable specific on‐resistance, confirming that the integrated AlN layer does not affect gate‑controlled channel charge. The proposed design achieves a 52% increase in breakdown voltage, attributed to improved potential distribution and charge balancing across the channel. Electrothermal simulations further demonstrate enhanced thermal robustness. Under high‑bias conditions ( V DS = 40 V), the peak junction temperature of proposed device reduces from 564 to 456 K. The current degradation rate decreases to 3.29% per W·mm −1 , approximately 2.3× lower than the conventional device. Dynamic R on analysis further confirms that the AlN‐BE MISHEMT suppresses transient resistance degradation, reducing Δ R on from 33% to 19% at V DS.q = 500 V. These results demonstrate that AlN buffer engineering effectively improves power‐handling capability and electrothermal reliability in GaN‐based power devices.