Microwave Performance of Ferroelectric-Gated GaN HEMTs

Hf0.5Zr0.5O2 (HZO) based ferroelectric gate high-electron-mobility transistors (FEHEMTs) on AlGaN/GaN heterostructures exhibiting programable threshold voltage are experimentally demonstrated. The RF behavior of ferroelectric-gated GaN-channel HEMTs has been measured and reported for the first time. Due to the ferroelectric gate stack, a programable threshold voltage range of 1.2 V was obtained. The RF characteristics show that the $f_{t}$ of conventional MISHEMTs and ferroelectric-gate HEMTs are similar, indicating that carrier transport is not strongly affected by the ferroelectric gate stack. However, significant dispersion is observed in both the RF transconductance and gate capacitance of the FEHEMTs, suggesting that in FEHEMTs the channel charge is insensitive to high frequency RF gate voltage signals. The results provide insights regarding the exploitation of FE gate stacks on GaN and related materials for future nonvolatile RF/microwave applications.