Fig. 3
From: Negative capacitance from the inductance of ferroelectric switching
Small-signal capacitance enhancement of a paraelectric hafnium oxide (HfO2) capacitor connected in series with a zirconium oxide (ZrO2) capacitor. a Schematic diagram of the ferroelectric ZrO2 (f-ZrO2)/HfO2, p-ZrO2/HfO2, and HfO2 capacitor structures. b The polarization–electric field (P–E) curves of the as-deposited paraelectric HfO2, paraelectric ZrO2 (p-ZrO2), and f-ZrO2 layers. c The small-signal capacitance of the p-ZrO2/HfO2, HfO2, f-ZrO2/HfO2 capacitor structures. The capacitance was probed at a direct-current (DC) voltage of 1 V and an alternate current (AC) perturbation of 30 mV. The f-ZrO2/HfO2 capacitor exhibits capacitance enhancement (×1.1) compared with the HfO2 capacitor, indicating the effect of negative capacitance as a paraelectric capacitor is connected in series with a ferroelectric capacitor. d The capacitance of the f-ZrO2/HfO2, p-ZrO2/HfO2, and HfO2 capacitor structures as a function of the frequency from 10 kHz to 1 MHz. The capacitance is almost free of frequency dispersion
