High performance negative capacitance field-effect transistor featuring low off-state current, high on/off current ratio, and steep sub-60 mV dec^-1 swing

In this work, we demonstrated that the 5-nm-thick HfAlO _x negative capacitance transistor (NCFET) with optimized Al doping can achieve a minimum 33 mV dec^-1 subthreshold swing (SS), an ultralow I _off of 7.44 fA μm^-1, and a high I _on /I _off ratio of 1.9 10⁸. The NC switching with sub-60 mV dec^-1 SS can be implemented from V _DS = 0.2 V to 0.8 V due to an ultralow off-state leakage current. The experimental results reveal that well-controlled Al doping in HfAlO _x not only reduces off-state leakage of the transistor, but also improves the ferroelectric NC effect to achieve a sub-60 mV dec^-1 switching under a favorably low sub-1 voltage. This scaled HfAlO _x NCFET with optimized Al doping and fluorine defect passivation shows the great potential for the application of low power logic devices.