skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: The effects of layering in ferroelectric Si-doped HfO{sub 2} thin films

Abstract

Atomic layer deposited Si-doped HfO{sub 2} thin films approximately 10 nm thick are deposited with various Si-dopant concentrations and distributions. The ferroelectric behavior of the HfO{sub 2} thin films are shown to be dependent on both the Si mol. % and the distribution of Si-dopants. Metal-ferroelectric-insulator-semiconductor capacitors are shown to exhibit a tunable remanent polarization through the adjustment of the Si-dopant distribution at a constant Si concentration. Inhomogeneous layering of Si-dopants within the thin films effectively lowers the remanent polarization. A pinched hysteresis loop is observed for higher Si-dopant concentrations and found to be dependent on the Si layering distribution.

Authors:
;  [1]; ;  [2]; ; ; ;  [3]
  1. Department of Electrical and Computer Engineering, University of Florida, Gainesville, Florida 32611 (United States)
  2. Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida 32611 (United States)
  3. Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27696-7907 (United States)
Publication Date:
OSTI Identifier:
22310900
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CAPACITORS; DEPOSITION; DISTRIBUTION; DOPED MATERIALS; FERROELECTRIC MATERIALS; HAFNIUM OXIDES; HYSTERESIS; LAYERS; METALS; POLARIZATION; SEMICONDUCTOR MATERIALS; SILICON ADDITIONS; THIN FILMS

Citation Formats

Lomenzo, Patrick D., Nishida, Toshikazu, E-mail: nishida@ufl.edu, Takmeel, Qanit, Moghaddam, Saeed, Zhou, Chuanzhen, Liu, Yang, Fancher, Chris M., and Jones, Jacob L. The effects of layering in ferroelectric Si-doped HfO{sub 2} thin films. United States: N. p., 2014. Web. doi:10.1063/1.4893738.
Lomenzo, Patrick D., Nishida, Toshikazu, E-mail: nishida@ufl.edu, Takmeel, Qanit, Moghaddam, Saeed, Zhou, Chuanzhen, Liu, Yang, Fancher, Chris M., & Jones, Jacob L. The effects of layering in ferroelectric Si-doped HfO{sub 2} thin films. United States. doi:10.1063/1.4893738.
Lomenzo, Patrick D., Nishida, Toshikazu, E-mail: nishida@ufl.edu, Takmeel, Qanit, Moghaddam, Saeed, Zhou, Chuanzhen, Liu, Yang, Fancher, Chris M., and Jones, Jacob L. Mon . "The effects of layering in ferroelectric Si-doped HfO{sub 2} thin films". United States. doi:10.1063/1.4893738.
@article{osti_22310900,
title = {The effects of layering in ferroelectric Si-doped HfO{sub 2} thin films},
author = {Lomenzo, Patrick D. and Nishida, Toshikazu, E-mail: nishida@ufl.edu and Takmeel, Qanit and Moghaddam, Saeed and Zhou, Chuanzhen and Liu, Yang and Fancher, Chris M. and Jones, Jacob L.},
abstractNote = {Atomic layer deposited Si-doped HfO{sub 2} thin films approximately 10 nm thick are deposited with various Si-dopant concentrations and distributions. The ferroelectric behavior of the HfO{sub 2} thin films are shown to be dependent on both the Si mol. % and the distribution of Si-dopants. Metal-ferroelectric-insulator-semiconductor capacitors are shown to exhibit a tunable remanent polarization through the adjustment of the Si-dopant distribution at a constant Si concentration. Inhomogeneous layering of Si-dopants within the thin films effectively lowers the remanent polarization. A pinched hysteresis loop is observed for higher Si-dopant concentrations and found to be dependent on the Si layering distribution.},
doi = {10.1063/1.4893738},
journal = {Applied Physics Letters},
number = 7,
volume = 105,
place = {United States},
year = {Mon Aug 18 00:00:00 EDT 2014},
month = {Mon Aug 18 00:00:00 EDT 2014}
}
  • Ferroelectric HfO{sub 2}-based thin films, which can exhibit ferroelectric properties down to sub-10 nm thicknesses, are a promising candidate for emerging high density memory technologies. As the ferroelectric thickness continues to shrink, the electrode-ferroelectric interface properties play an increasingly important role. We investigate the TaN interface properties on 10 nm thick Si-doped HfO{sub 2} thin films fabricated in a TaN metal-ferroelectric-metal stack which exhibit highly asymmetric ferroelectric characteristics. To understand the asymmetric behavior of the ferroelectric characteristics of the Si-doped HfO{sub 2} thin films, the chemical interface properties of sputtered TaN bottom and top electrodes are probed with x-ray photoelectron spectroscopy. Ta-Omore » bonds at the bottom electrode interface and a significant presence of Hf-N bonds at both electrode interfaces are identified. It is shown that the chemical heterogeneity of the bottom and top electrode interfaces gives rise to an internal electric field, which causes the as-grown ferroelectric domains to preferentially polarize to screen positively charged oxygen vacancies aggregated at the oxidized bottom electrode interface. Electric field cycling is shown to reduce the internal electric field with a concomitant increase in remanent polarization and decrease in relative permittivity. Through an analysis of pulsed transient switching currents, back-switching is observed in Si-doped HfO{sub 2} thin films with pinched hysteresis loops and is shown to be influenced by the internal electric field.« less
  • Ferroelectric HfO{sub 2} thin films 10 nm thick are simultaneously doped with Al and Si. The arrangement of the Al and Si dopant layers within the HfO{sub 2} greatly influences the resulting ferroelectric properties of the polycrystalline thin films. Optimizing the order of the Si and Al dopant layers led to a remanent polarization of ∼20 μC/cm{sup 2} and a coercive field strength of ∼1.2 MV/cm. Post-metallization anneal temperatures from 700 °C to 900 °C were used to crystallize the Al and Si doped HfO{sub 2} thin films. Grazing incidence x-ray diffraction detected differences in peak broadening between the mixed Al and Si doped HfO{submore » 2} thin films, indicating that strain may influence the formation of the ferroelectric phase with variations in the dopant layering. Endurance characteristics show that the mixed Al and Si doped HfO{sub 2} thin films exhibit a remanent polarization greater than 15 μC/cm{sup 2} up to 10{sup 8} cycles.« less
  • 0.07YO{sub 1.5}-0.93HfO{sub 2} (YHO7) films were prepared on various substrates by pulse laser deposition at room temperature and subsequent heat treatment to enable a solid phase reaction. (111)-oriented 10 wt. % Sn-doped In{sub 2}O{sub 3}(ITO)//(111) yttria-stabilized zirconia, (111)Pt/TiO{sub x}/SiO{sub 2}/(001)Si substrates, and (111)ITO/(111)Pt/TiO{sub x}/SiO{sub 2}/(001)Si substrates were employed for film growth. In this study, X-ray diffraction measurements including θ–2θ measurements, reciprocal space mappings, and pole figure measurements were used to study the films. The film on (111)ITO//(111)yttria-stabilized zirconia was an (111)-orientated epitaxial film with ferroelectric orthorhombic phase; the film on (111)ITO/(111)Pt/TiO{sub x}/SiO{sub 2}/(001)Si was an (111)-oriented uniaxial textured film with ferroelectricmore » orthorhombic phase; and no preferred orientation was observed for the film on the (111)Pt/TiO{sub x}/SiO{sub 2}/(001)Si substrate, which does not contain ITO. Polarization–hysteresis measurements confirmed that the films on ITO covered substrates had saturated ferroelectric hysteresis loops. A remanent polarization (P{sub r}) of 9.6 and 10.8 μC/cm{sup 2} and coercive fields (E{sub c}) of 1.9 and 2.0 MV/cm were obtained for the (111)-oriented epitaxial and uniaxial textured YHO7 films, respectively. These results demonstrate that the (111)-oriented ITO bottom electrodes play a key role in controlling the orientation and ferroelectricity of the phase formation of the solid films deposited at room temperature.« less
  • Orientation control of {100}-oriented epitaxial orthorhombic 0.07YO{sub 1.5}-0.93HfO{sub 2} films grown by pulsed laser deposition was investigated. To achieve in-plane lattice matching, indium tin oxide (ITO) and yttria-stabilized zirconia (YSZ) were selected as underlying layers. We obtained (100)- and (001)/(010)-oriented films on ITO and YSZ, respectively. Ferroelastic domain formation was confirmed for both films by X-ray diffraction using the superlattice diffraction that appeared only for the orthorhombic symmetry. The formation of ferroelastic domains is believed to be induced by the tetragonal–orthorhombic phase transition upon cooling the films after deposition. The present results demonstrate that the orientation of HfO{sub 2}-based ferroelectricmore » films can be controlled in the same manner as that of ferroelectric films composed of conventional perovskite-type material such as Pb(Zr, Ti)O{sub 3} and BiFeO{sub 3}.« less
  • We report on the growth of highly oriented HfO{sub 2} thin films of monoclinic phase stabilized by 5% Co doping on (001) yttrium-stabilized zirconia (YSZ) using pulsed-laser deposition at 700 deg. C at an oxygen partial pressure of 10{sup -4} Torr. On the other hand, pure HfO{sub 2} of such quality did not grow on YSZ in wide range of growth parameters. Rutherford backscattering-ion channeling in this film showed a 24% minimum yield ({chi}{sub min}) indicating highly oriented film growth, while hardly any ion channeling was observed in the undoped sample. High-resolution transmission electron microscopy revealed a sharp interface, andmore » no signature of Co clusters. Electron energy loss spectroscopy showed that Co is in the 2+ state. Attempts were also made to grow films on a (001) Si substrate, and the results showed a very low ion channeling yield ({approx}8%)« less