Effect of AlScN Polarization Suppression in the Access-Region for Ferroelectric GaN HEMTs

초록

We investigate the impact of access-region AlScN polarization removal on the electrical and memory characteristics of ferroelectric Al0.7Sc0.3N/HfO2/AlGaN/GaN high-electron-mobility transistors ferroelectric high-electron-mobility transistors (FeHEMTs) with nonrecessed and recessed gate structures. Using a self-aligned gate etch, in nonrecessed devices, we suppress access-region polarization and observe a pronounced increase in the memory-window (MW) from 0.82 to 1.35 V in DC sweeps and from 1.61 to 2.90 V under pulsed bias along with suppression of negative drain-induced barrier lowering (DIBL) and stabilization of V-th. Recessed device showed negligible MW change from similar to 3.02-3.05 V, indicating strong gate control attributed to the thin AlGaN barrier. Pulse modulation and corresponding MW mapping results further confirm that access-region polarization significantly affects polarization switching in the nonrecessed devices. Both retention and endurance improve markedly after polarization suppression, particularly in the nonrecessed structure due to reduced charge trapping and stabilized polarization after the access-region AlScN removal. These results establish a practical device design guideline in FeHEMT.

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