Super Junction Negative Capacitance AlGaN/GaN HEMT for Ku-band Applications

This work presents a novel semiconductor device architecture—the Super Junction Negative Capacitance High Electron Mobility Transistor (SJNCHEMT)—which integrates a ferroelectric Hafnium Zirconium Oxide (HZO) layer into the gate stack of an AlGaN/GaN-based HEMT. The integration of negative capacitance not only enhances the internal gate voltage but also significantly improves key device metrics. Using Technology Computer-Aided Design (TCAD) simulations, the proposed SJNCHEMT demonstrates an ON current of 682 mA/mm, subthreshold swing of 40 mV/decade, and a peak transconductance of 89 mS/mm – values markedly superior to those of conventional super junction HEMTs. Furthermore, the device exhibits reduced ON-resistance and mitigated current collapse behavior. A systematic study on the recessed height of the undoped GaN cap layer reveals tunability of the threshold voltage, enabling normally-off operation with a positive threshold voltage of 0.75 V for a recess depth of 35 nm. Peak values of transconductance (120 mS/mm) and cut-off frequency (14.9 GHz) are achieved through structural optimization. Comparative analysis with existing NCHEMT designs confirms the superior performance and design flexibility of SJNCHEMTs, positioning them as strong candidates for next-generation high-speed and high-power electronics.