Energy-Efficient HfAlOx NCFET: Using Gate Strain and Defect Passivation to Realize Nearly Hysteresis-Free Sub-25mV/dec Switch with Ultralow Leakage

Abstract

We experimentally demonstrated that ferroelectric HfAlOx negative capacitance FETs using gate strain and defect passivation can realize a nearly hysteresis-free forward/reverse swing of < 25 mV/dec for symmetric switch, a wide sub-60 mV/dec SS range over 4 decade of I-DS to reach an ultralow I-off of 4 fA/mu m, and a very high I-on/I-off ratio of > 10(8). Under the influence of gate strain and negative capacitance, the NCFETs exhibits 66% I-on enhancement and 27% V-T reduction. In addition, the fluorine defect passivation reduces oxygen vacancies of gate stack to further mitigate interface depolarization field and help to significantly reinforce surface potential amplification effect during NC operation.