TY - JOUR
KW - Electricity
KW - Film
KW - Perovskite
KW - Silicon
KW - Thickness
KW - Metal oxide
KW - Polarization
KW - Ferroelectricity
KW - Fluoride
KW - Fluorite
KW - Hafnium
KW - Hafnium oxide
KW - Unclassified drug
KW - Electric field
KW - Superconductivity
KW - Symmetry
KW - Article
KW - Chemical parameters
KW - Chemical structure
KW - Controlled study
KW - Electrical parameters
KW - Photon
KW - Priority journal
KW - Reverse size effect
AU - S.S Cheema
AU - D Kwon
AU - N Shanker
AU - R. dos Reis
AU - S.-L Hsu
AU - J Xiao
AU - H Zhang
AU - R Wagner
AU - A Datar
AU - M.R McCarter
AU - C.R Serrao
AU - A.K Yadav
AU - G Karbasian
AU - C.-H Hsu
AU - A.J Tan
AU - L.-C Wang
AU - V Thakare
AU - X Zhang
AU - A Mehta
AU - E Karapetrova
AU - R.V Chopdekar
AU - P Shafer
AU - E Arenholz
AU - C Hu
AU - R Proksch
AU - Ramamoorthy Ramesh
AU - J Ciston
AU - S Salahuddin
AB - Ultrathin ferroelectric materials could potentially enable low-power perovskite ferroelectric tetragonality logic and nonvolatile memories1,2. As ferroelectric materials are made thinner, however, the ferroelectricity is usually suppressed. Size effects in ferroelectrics have been thoroughly investigated in perovskite oxides—the archetypal ferroelectric system3. Perovskites, however, have so far proved unsuitable for thickness scaling and integration with modern semiconductor processes4. Here we report ferroelectricity in ultrathin doped hafnium oxide (HfO2), a fluorite-structure oxide grown by atomic layer deposition on silicon. We demonstrate the persistence of inversion symmetry breaking and spontaneous, switchable polarization down to a thickness of one nanometre. Our results indicate not only the absence of a ferroelectric critical thickness but also enhanced polar distortions as film thickness is reduced, unlike in perovskite ferroelectrics. This approach to enhancing ferroelectricity in ultrathin layers could provide a route towards polarization-driven memories and ferroelectric-based advanced transistors. This work shifts the search for the fundamental limits of ferroelectricity to simpler transition-metal oxide systems—that is, from perovskite-derived complex oxides to fluorite-structure binary oxides—in which ‘reverse’ size effects counterintuitively stabilize polar symmetry in the ultrathin regime. © 2020, The Author(s), under exclusive licence to Springer Nature Limited.
BT - Nature
DO - 10.1038/s41586-020-2208-x
LA - eng
M1 - 7804
N1 - cited By 0
N2 - Ultrathin ferroelectric materials could potentially enable low-power perovskite ferroelectric tetragonality logic and nonvolatile memories1,2. As ferroelectric materials are made thinner, however, the ferroelectricity is usually suppressed. Size effects in ferroelectrics have been thoroughly investigated in perovskite oxides—the archetypal ferroelectric system3. Perovskites, however, have so far proved unsuitable for thickness scaling and integration with modern semiconductor processes4. Here we report ferroelectricity in ultrathin doped hafnium oxide (HfO2), a fluorite-structure oxide grown by atomic layer deposition on silicon. We demonstrate the persistence of inversion symmetry breaking and spontaneous, switchable polarization down to a thickness of one nanometre. Our results indicate not only the absence of a ferroelectric critical thickness but also enhanced polar distortions as film thickness is reduced, unlike in perovskite ferroelectrics. This approach to enhancing ferroelectricity in ultrathin layers could provide a route towards polarization-driven memories and ferroelectric-based advanced transistors. This work shifts the search for the fundamental limits of ferroelectricity to simpler transition-metal oxide systems—that is, from perovskite-derived complex oxides to fluorite-structure binary oxides—in which ‘reverse’ size effects counterintuitively stabilize polar symmetry in the ultrathin regime. © 2020, The Author(s), under exclusive licence to Springer Nature Limited.
PB - Nature Research
PY - 2020
SP - 478
EP - 482
T2 - Nature
TI - Enhanced ferroelectricity in ultrathin films grown directly on silicon
VL - 580
SN - 00280836
ER -