Evaluation of a GaN HEMT Half-Bridge embedded to a Multilayer Aluminum Nitride Substrate

Power electronic systems employing wide-bandgap GaN transistors promise high efficiency operation and superior power density but require minimized parasitic circuit elements and an effective cooling concept. This paper presents a halfbridge module integrating two GaN HEMTs with their gate drive stages and the DC-link capacitance on a multilayer AlN-substrate. The small layer distance of 10 micrometer achieved on the GaN half-bridge module allows for minimization of layoutrelated parasitic inductances. The parasitic circuit elements are evaluated and compared to conventional 4-layer PCB design using 3D-FEM field simulation and measurements. Due to a lateral commutation loop design, the GaN half-bridge module achieves notably lower parasitic capacitances but also a smaller commutation loop inductance. The thermal characterization of the fabricated half-bridge module validates the high cooling capability introduced by the AlN-substrate. The switching characteristics of the proposed GaN half-bridge module are studied in hard-switched mode.