Ferroelectric Properties and Polarization Fatigue of La:HfO₂ Thin‐Film Capacitors

Abstract

Recently, doped HfO2 thin films have attracted considerable attention because of promising applications in complementary metal–oxide–semiconductor (CMOS)‐compatible ferroelectric memories. Herein, the ferroelectric properties and polarization fatigue of La:HfO2 thin‐film capacitors are reported. By varying the substrate lattice constant and film thickness, a robust remanent polarization of ≈16 μC cm−2 is achieved in a 12 nm‐thick Pt/La:HfO2/La0.67Sr0.33MnO3 capacitor. Fatigue measurements are conducted using designed pulse sequences, in which the voltage, pulse width, and interval time are changed to observe the evolution of switchable polarization with increasing cycles. Severe fatigue is observed when the La:HfO2 capacitors are partially switched and the interval between the bipolar switching is elongated. These behaviors may be ascribed to the domain wall pinning scenario, in which domain switching is blocked by the migration and aggregation of charges on non‐electroneutral walls. Further analysis of the fatigue behaviors with a nucleation‐limited‐switching model shows that the mean time and activation field for polarization switching are increased in fatigued La:HfO2 capacitors because electrical stimuli are required to disperse the aggregated charges before the domains are set free. These results facilitate the design and fabrication of HfO2‐based ferroelectric memories with improved device reliability.

Hafnium Oxide (HfO2) – A Multifunctional Oxide: A Review on the Prospect and Challenges of Hafnium Oxide in Resistive Switching and Ferroelectric Memories

“…[412,413] Therefore, the formation of large grains during the fabrication process may increase the number of cycles to fatigue. [414][415][416] Huang et al [412] showed that the domain-wall pinning caused by carrier injection at [315] Copyright 2021, ACS.…”

“…[ 412,413 ] Therefore, the formation of large grains during the fabrication process may increase the number of cycles to fatigue. [ 414–416 ] Huang et al [ 412 ] showed that the domain‐wall pinning caused by carrier injection at shallow defect centers is the major fatigue mechanism of the HfO 2 ‐based ferroelectric materials. A fatigue‐free system was achieved by subsequent annealing, confirming the shallow trap characteristic of the domain wall pinning defects.…”

An Overview of Ferroelectric Hafnia and Epitaxial Growth

“…(1-x)HfO 2 -xZrO 2 /Si(100) [75] HZO/LSMO/(001)STO [139] 800 0.1 18 20 No HZO/LSMO/LNO/CeO 2 /YSZ/Si(001) [57,102] 800 0.1 9.5 20 No HZO/LSMO/(001)STO [45] 800 0.1 6.9 24 No HZO/LSMO/STO [54,84]b) 800 0.1 1.5-27 34 No HZO/LSMO/(001)STO [139] 800 0.1 9, 18 20 No HZO/LSMO/(001)S [60,83,140,141]c) 800 0.1 9.5 5-25 -HLO/LSMO/(001)STO [142] 600 0.1 12 16 -HZLO/LSMO/(001)STO [38] 800 0.1 4.5-13 21-28 No HZLO/LSMO/STO/(001)Si [38] HZO/LSMO/STO/Si [55] 800 0.1…”

Epitaxial ferroelectric interfacial devices

“…However, a growing number of studies have reported the growth of epitaxial ferroelectric HfO 2 films. [387][388][389][390][391][392][393][394][395][396][397][398] One example is the epitaxial growth of 15-20 nm YO 1.5 -substituted HfO 2 films by pulsed laser deposition on [100]-oriented yttrium oxide-stabilized zirconium oxide (YSZ) substrates, 387 and on YSZ(110) single crystals using Sn-doped In 2 O 3 (ITO) as a bottom electrode, 389 where large ferroelectric polarizations and an estimated critical temperature of 723 K were observed. A cross-sectional annular bright field STEM image of a ca.…”