Noise Optimization in AlPN/GaN HEMTs for High-Frequency Circuits

Although aluminum phosphide nitride/gallium nitride (AlPN/GaN) high electron mobility transistors (HEMTs) have been extensively investigated for high-power and high-frequency applications, systematic studies on their intrinsic radio frequency (RF) noise characteristics remain limited. In this work, the RF noise performance of AlPN/GaN HEMTs is investigated using a physics-based TCAD framework, in which a conventional AlGaN/GaN HEMT is first calibrated against the published electrical characteristics of a fabricated device and subsequently modified by replacing the AlGaN barrier with an AlPN barrier while maintaining identical device geometry and operating conditions. The effects of phosphorus mole fraction, AlPN barrier thickness, and substrate material on intrinsic noise behavior are systematically analyzed to optimize device performance Optimizing the phosphorus composition modifies the polarization-induced charge and carrier confinement at the AlPN/GaN heterointerface, resulting in improved carrier transport and reduced simulated RF noise. A comparative study of silicon (Si) and silicon carbide (SiC) substrates further demonstrates that the superior thermal conductivity and lattice compatibility of SiC improves heat dissipation and suppress defect related fluctuations, resulting in lower intrinsic device noise. The optimized AlPN/GaN HEMT on a SiC substrate achieves a minimum noise figure of 1.8 dB at 20 GHz, demonstrating the effectiveness of barrier engineering and substrate optimization for improving the intrinsic RF noise performance of AlPN/GaN HEMTs and providing design guidelines for next-generation low-noise microwave and RF front-end applications.