Extended Data Fig. 10: Ultrathin HZO ferroelectric tunnel junction.
From: Enhanced ferroelectricity in ultrathin films grown directly on silicon
a, c, Tunnel current–voltage characterization of Si(p++)/SiO2(1 nm)/HZO(∼1 nm)/W capacitor devices—demonstrated for ten-cycle HZO with Hf:Zr composition 4:1 (a) and 1:1 (c)—as a function of the write pulse (to set the ferroelectric polarization state). Tunnelling electroresistance behaviour is demonstrated for ±2 V write and 100 mV read. Insets, linear-scale current–voltage characteristics of the two polarization-driven current states. b, d, Tunnelling electroresistance hysteresis map as a function of write voltage (demonstrated for ten-cycle HZO with Hf:Zr composition 4:1 (b) and 1:1 (d)) measured at 200 mV read voltage. The abrupt hysteretic behaviour and saturating tunnelling electroresistance is characteristic of polarization-driven switching67, as opposed to filamentary-based switching caused by electrochemical migration and/or oxygen vacancy motion (Methods). e, Current–voltage hysteresis sweeps ruling out non-polarization-driven resistive switching mechanisms (Methods). The device demonstrates current–voltage hysteresis at low voltage and voltage polarity-independent current–voltage hysteresis sense: both negative-positive-negative voltage polarity (left) and positive-negative-positive voltage polarity (right) demonstrate counter-clockwise hysteresis. Such behaviour rules out resistive switching mediated by dielectric breakdown and filamentary mechanisms66 and is consistent with polarization-driven switching.
