Unipolar Parity of Ferroelectric-Antiferroelectric Characterized by Junction Current in Crystalline Phase Hf1−xZrxO2 Diodes

Abstract

Ferroelectric (FE) Hf1−xZrxO2 is a potential candidate for emerging memory in artificial intelligence (AI) and neuromorphic computation due to its non-volatility for data storage with natural bi-stable characteristics. This study experimentally characterizes and demonstrates the FE and antiferroelectric (AFE) material properties, which are modulated from doped Zr incorporated in the HfO2-system, with a diode-junction current for memory operations. Unipolar operations on one of the two hysteretic polarization branch loops of the mixed FE and AFE material give a low program voltage of 3 V with an ON/OFF ratio >100. This also benefits the switching endurance, which reaches >109 cycles. A model based on the polarization switching and tunneling mechanisms is revealed in the (A)FE diode to explain the bipolar and unipolar sweeps. In addition, the proposed FE-AFE diode with Hf1−xZrxO2 has a superior cycling endurance and lower stimulation voltage compared to perovskite FE-diodes due to its scaling capability for resistive FE memory devices.

Fatigue Mechanism of Antiferroelectric Hf0.1Zr0.9O2 Toward Endurance Immunity by Opposite Polarity Cycling Recovery (OPCR) for eDRAM

“…For bipolar operation, the typical FE and AFE characteristics are exhibited with bipolar sweeps for Zr = 50% and 90%, respectively. For the unipolar sweeps, Zr = 50% and 90% show a nearly paraelectric and single loop, respectively [8]. Therefore, Zr = 50% and 90% HZO are denoted as FE and AFE in this work, respectively.…”

“…P-V of Zr = 50% and 90% of HZO for (a) bipolar and (b) unipolar sweeps. For the unipolar sweeps, Zr = 50% and 90% show a nearly paraelectric and single loop, respectively[8]. (c) Available ratio of AFE switching polarization is obviously higher than FE with t p < 1 µs [6],[7].…”

Recent Research for HZO-Based Ferroelectric Memory towards In-Memory Computing Applications

“…In a conventional metal-semiconductor contact, a spatial charge region in the semiconductor is formed to align the Fermi level, and a charge exacts same and opposite exists on the interface of the metal. The interfacial charge of a single ferroelectric Schottky diode and the band diagram is therefore subject to continuous and sustainable variability by the application of an external electric field [50,51]. The positive and negative polarization charges result in the accumulation of electrons that, respectively reduce the barrier height and increase the band bending by the positively charged oxygen vacancy.…”