Low Thermal Resistance Architectures for AlGaN‐Based Semiconductor Devices

ABSTRACT Next‐generation high‐power radio‐frequency (RF) devices increasingly demand transistors that operate efficiently with high gain at high frequencies. High‐aluminum‐content ultrawide‐bandgap (UWBG) AlGaN alloys have shown great potential for enabling such high‐frequency RF technologies. However, the widespread adoption of AlGaN‐based RF devices is limited by thermal‐management challenges arising from the intrinsically low thermal conductivity of AlGaN, which leads to higher device thermal resistance for a given geometry compared to GaN RF devices. As a result, these next‐generation devices are highly susceptible to self‐heating. This study investigates the thermal behavior of UWBG AlGaN devices, focusing on the effects of AlGaN channel thickness, substrate technology, and high‐k material integration on reducing device thermal resistance to enable high‐power operation. Experimental results demonstrate a record‐low thermal resistance of 3.96 /W when an AlN substrate is employed and the AlGaN channel thickness is reduced to 5 nm. These findings provide valuable insights into mitigating thermal limitations in UWBG devices through device‐level engineering and the strategic integration of high‐k materials.