Advances in GaN power HEMT design and reliability for high-performance power applications

Gallium nitride (GaN) high-electron-mobility transistors (HEMTs) now anchor fast power converters, 5 G radios, and emerging EV platforms. This review explores advanced strategies for optimizing GaN HEMTs, focusing on design parameters critical to enhance performance. It evaluates device architectures, operational characteristics, and reliability challenges. The optimization of device architecture incorporates nucleation layers, back barriers, GaN cap layers, field plate engineering, surface passivation, and engineered buffer structures like graded Al x Ga 1-x N, superlattice buffers, and doping techniques. The review also analyzes operational performance for depletion mode (D-mode) and enhancement mode (E-mode) devices, highlighting their suitability for power electronics through techniques such as AlGaN barrier recess, fluorine plasma treatment, and cascode configurations. The impact of various substrate materials (Si, sapphire, bulk GaN, SiC) on thermal management and lattice compatibility is highlighted. Advanced architectures, including vertical GaN HEMTs, N-polar orientations, and double-channel structures, are discussed. The review further discusses innovative approaches for mitigating dynamic ON-resistance degradation and dispersion effects using optimized field plates and passivation. It examines key reliability challenges, including threshold voltage instability, time-dependent dielectric breakdown, bias temperature instability, buffer traps, and hot carrier injection. AI-assisted design methodologies and monolithic integration techniques are assessed in relation to manufacturing scalability. Finally, the review emphasizes the requirement for integrated optimization of epitaxial growth, device architecture, and testing protocols to advance GaN HEMT technology for high-frequency and power applications, thereby laying a foundation for robust device development.