A p-Type Ferroelectric Field-Effect Transistor Using Ultrathin Hafnium Aluminum Oxide

Herein, the electrical characteristics of a p-type negative-capacitance field-effect transistor are investigated using an ultrathin 2.5 nm-thick HfAlO_x. The optimized performance exhibits a steep subthreshold slope of 35 mV dec⁻¹, a negligible hysteresis of 4 mV, and a low off-state current of 3 × 10⁻¹³A μm⁻¹. Appropriate aluminum doping into HfAlO_x film can not only improve the leakage current but also stabilize the negative-capacitance matching. The prominent improvement on the capacitance matching and ferroelectricity can be ascribed to the reduced defect traps and less dielectric crystalline phase during annealing, which is important for the practical application of energy-efficient logic devices.