@article{horgan_hsain_jones_grieger_2023, title={Development and application of screening-level risk analysis for emerging materials}, volume={35}, ISSN={2214-9937}, url={http://dx.doi.org/10.1016/j.susmat.2022.e00524}, DOI={10.1016/j.susmat.2022.e00524}, abstractNote={Analysis of a material's impact on society is increasingly recognized as a necessary step in materials development, especially in the area of lead-free piezoelectrics. Evaluations of the environmental, health, and societal impacts that occur throughout the material's life cycle are critical for determining the viability of lead-free alternatives. Risk screening approaches, such as the screening-level Emerging Materials Risk Analysis (EMRA) proposed in this work, may help researchers compare materials or material production routes to determine more sustainable solutions. As a first demonstration of its utility in the development of lead-free piezoelectrics, the approach introduced in this paper is applied to piezoelectric HfO2 (hafnia) to compare mining and processing routes and to elucidate the more sustainable route for HfO2 production. This paper aims to exemplify how the EMRA risk screening approach incorporates perspectives on environmental, health, and societal impacts into the materials research process by providing a relative risk screening evaluation of different material processing routes and/or different materials. Results from applying EMRA to hafnia show that the major known environmental impacts of hafnia mining and processing involve ecosystem destruction and heavy use of fossil fuels and electricity; health impacts related to potentially unsafe working conditions and potential exposure to radioactive elements; and societal impacts including land disputes and supply concerns. Results also demonstrate that the more sustainable production route currently available includes commercial wet mining with land rehabilitation followed by beneficiation via wet processes with consistent personal protective equipment use and water recycling. Almost all of the previously-mentioned impacts are avoided in this life cycle route. Outcomes from this analysis identify hafnia as a potentially sustainable replacement for certain applications of PZT and therefore encourage continued development of the material. Future efforts will test EMRA on a wide variety of other materials and revise the approach accordingly.}, journal={Sustainable Materials and Technologies}, publisher={Elsevier BV}, author={Horgan, Madison D. and Hsain, H. Alex and Jones, Jacob L. and Grieger, Khara D.}, year={2023}, month={Apr}, pages={e00524} }
 @article{hsain_lee_lancaster_lomenzo_xu_mikolajick_schroeder_parsons_jones_2023, title={Reduced fatigue and leakage of ferroelectric TiN/Hf0.5Zr0.5O2/TiN capacitors by thin alumina interlayers at the top or bottom interface}, volume={34}, ISSN={["1361-6528"]}, DOI={10.1088/1361-6528/acad0a}, abstractNote={Abstract}, number={12}, journal={NANOTECHNOLOGY}, author={Hsain, H. Alex and Lee, Younghwan and Lancaster, Suzanne and Lomenzo, Patrick D. and Xu, Bohan and Mikolajick, Thomas and Schroeder, Uwe and Parsons, Gregory N. and Jones, Jacob L.}, year={2023}, month={Mar} }
 @article{silva_alcala_avci_barrett_begon-lours_borg_byun_chang_cheong_choe_et al._2023, title={Roadmap on ferroelectric hafnia- and zirconia-based materials and devices}, volume={11}, ISSN={["2166-532X"]}, DOI={10.1063/5.0148068}, abstractNote={Ferroelectric hafnium and zirconium oxides have undergone rapid scientific development over the last decade, pushing them to the forefront of ultralow-power electronic systems. Maximizing the potential application in memory devices or supercapacitors of these materials requires a combined effort by the scientific community to address technical limitations, which still hinder their application. Besides their favorable intrinsic material properties, HfO2–ZrO2 materials face challenges regarding their endurance, retention, wake-up effect, and high switching voltages. In this Roadmap, we intend to combine the expertise of chemistry, physics, material, and device engineers from leading experts in the ferroelectrics research community to set the direction of travel for these binary ferroelectric oxides. Here, we present a comprehensive overview of the current state of the art and offer readers an informed perspective of where this field is heading, what challenges need to be addressed, and possible applications and prospects for further development.}, number={8}, journal={APL MATERIALS}, author={Silva, Jose P. B. and Alcala, Ruben and Avci, Uygar E. and Barrett, Nick and Begon-Lours, Laura and Borg, Mattias and Byun, Seungyong and Chang, Sou-Chi and Cheong, Sang-Wook and Choe, Duk-Hyun and et al.}, year={2023}, month={Aug} }
 @article{hsain_lee_lomenzo_alcala_xu_mikolajick_schroeder_parsons_jones_2023, title={Wake-up free ferroelectric hafnia-zirconia capacitors fabricated via vacuum-maintaining atomic layer deposition}, volume={133}, ISSN={["1089-7550"]}, url={https://doi.org/10.1063/5.0147124}, DOI={10.1063/5.0147124}, abstractNote={Ferroelectric hafnium-zirconium oxide (HZO) is an excellent candidate for low-power non-volatile memory applications due to its demonstrated ferroelectricity at the nanoscale and compatibility with silicon-based technologies. The interface of HZO in contact with its electrode, typically TiN in a metal–ferroelectric–metal (MFM) capacitor configuration, is of particular interest because factors, such as volume confinement, impurity concentration, interfacial layers, thermal expansion mismatch, and defect trapping, are believed to play a crucial role in the ferroelectric performance of HZO-based devices. Processing variables, such as precursor type, oxygen source, dose duration, and deposition temperature, are known to strongly affect the quality of the oxide–metal interface. However, not many studies have focused on the effect of breaking or maintaining vacuum during MFM deposition. In this study, sequential, no-atmosphere processing (SNAP) is employed to avoid atmospheric exposure, where electrode TiN and ferroelectric HZO are deposited sequentially in the atomic layer deposition chamber without breaking vacuum. The effect of breaking vacuum during the sequential deposition steps is elucidated by fabricating and characterizing MFM capacitors with and without intentional vacuum breaks prior to the deposition of the HZO and top TiN. Using x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry (ToF-SIMS), we reveal that breaking vacuum after bottom TiN electrode deposition leads to interfacial oxidation and increased carbon contamination, which preferentially stabilizes the non-ferroelectric tetragonal phase and lead to diminished remanent polarization. Avoiding carbon impurities and interfacial TiOx at the HZO and TiN interface using SNAP leads to heightened remanent polarization, reduced leakage current density, and elimination of the wake-up effect. Our work highlights the effect of vacuum breaking on the processing-structure-properties of HZO-based capacitors, revealing that maintaining vacuum can significantly improve ferroelectric properties.}, number={22}, journal={JOURNAL OF APPLIED PHYSICS}, author={Hsain, H. Alex and Lee, Younghwan and Lomenzo, Patrick D. and Alcala, Ruben and Xu, Bohan and Mikolajick, Thomas and Schroeder, Uwe and Parsons, Gregory N. and Jones, Jacob L.}, year={2023}, month={Jun} }
 @article{hsain_lee_lancaster_materano_alcala_xu_mikolajick_schroeder_parsons_jones_2022, title={Role of Oxygen Source on Buried Interfaces in Atomic-Layer- Deposited Ferroelectric Hafnia-Zirconia Thin Films}, volume={9}, ISSN={["1944-8252"]}, url={https://doi.org/10.1021/acsami.2c11073}, DOI={10.1021/acsami.2c11073}, abstractNote={Hafnia-zirconia (HfO2-ZrO2) solid solution thin films have emerged as viable candidates for electronic applications due to their compatibility with Si technology and demonstrated ferroelectricity at the nanoscale. The oxygen source in atomic layer deposition (ALD) plays a crucial role in determining the impurity concentration and phase composition of HfO2-ZrO2 within metal-ferroelectric-metal devices, notably at the Hf0.5Zr0.5O2 /TiN interface. The interface characteristics of HZO/TiN are fabricated via sequential no-atmosphere processing (SNAP) with either H2O or O2-plasma to study the influence of oxygen source on buried interfaces. Time-of-flight secondary ion mass spectrometry reveals that HZO films grown via O2-plasma promote the development of an interfacial TiOx layer at the bottom HZO/TiN interface. The presence of the TiOx layer leads to the development of 111-fiber texture in HZO as confirmed by two-dimensional X-ray diffraction (2D-XRD). Structural and chemical differences between HZO films grown via H2O or O2-plasma were found to strongly affect electrical characteristics such as permittivity, leakage current density, endurance, and switching kinetics. While HZO films grown via H2O yielded a higher remanent polarization value of 25 μC/cm2, HZO films grown via O2-plasma exhibited a comparable Pr of 21 μC/cm2 polarization and enhanced field cycling endurance limit by almost 2 orders of magnitude. Our study illustrates how oxygen sources (O2-plasma or H2O) in ALD can be a viable way to engineer the interface and properties in HZO thin films.}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Hsain, Hanan Alexandra and Lee, Younghwan and Lancaster, Suzanne and Materano, Monica and Alcala, Ruben and Xu, Bohan and Mikolajick, Thomas and Schroeder, Uwe and Parsons, Gregory N. and Jones, Jacob L.}, year={2022}, month={Sep} }
 @article{hsain_lee_lancaster_materano_alcala_xu_mikolajick_schroeder_parsons_jones_2022, title={Role of Oxygen Source on Buried Interfaces in Atomic-Layer- Deposited Ferroelectric Hafnia-Zirconia Thin Films}, volume={14}, ISSN={["1944-8252"]}, DOI={10.1021/acsami.2c1107342232}, number={37}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Hsain, Hanan Alexandra and Lee, Younghwan and Lancaster, Suzanne and Materano, Monica and Alcala, Ruben and Xu, Bohan and Mikolajick, Thomas and Schroeder, Uwe and Parsons, Gregory N. and Jones, Jacob L.}, year={2022}, month={Sep}, pages={42232–42244} }
 @article{payne_alex hsain_lee_strnad_jones_hanrahan_2022, title={Thermal stability of antiferroelectric-like Al:HfO2 thin films with TiN or Pt electrodes}, volume={120}, ISSN={["1077-3118"]}, DOI={10.1063/5.0083656}, abstractNote={HfO2-based antiferroelectric-like thin films are increasingly being considered for commercial devices. However, even with initial promise, the temperature sensitivity of electrical properties such as loss tangent and leakage current remains unreported. 50 nm thick, 4 at. % Al-doped HfO2 thin films were synthesized via atomic layer deposition with both top and bottom electrodes being TiN or Pt. A study of their capacitance vs temperature showed that the Pt/Al:HfO2/Pt had a relative dielectric permittivity of 23.30 ± 0.06 at room temperature with a temperature coefficient of capacitance (TCC) of 78 ± 86 ppm/°C, while the TiN/Al:HfO2/TiN had a relative dielectric permittivity of 32.28 ± 0.14 at room temperature with a TCC of 322 ± 41 ppm/°C. The capacitance of both devices varied less than 6% over 1 to 1000 kHz from −125 to 125 °C. Both capacitors maintained loss tangents under 0.03 and leakage current densities of 10−9–10−7 A/cm2 between −125 and 125 °C. The TiN/Al:HfO2/TiN capacitor maintained an energy storage density (ESD) of 18.17 ± 0.79 J/cm3 at an efficiency of 51.79% ± 2.75% over the −125 to 125 °C range. The Pt/Al:HfO2/Pt capacitor also maintained a stable ESD of 9.83 ± 0.26 J/cm3 with an efficiency of 62.87% ± 3.00% over the same temperature range. Such low losses in both capacitors along with their thermal stability make antiferroelectric-like, Al-doped HfO2 thin films a promising material for temperature-stable microelectronics.}, number={23}, journal={APPLIED PHYSICS LETTERS}, author={Payne, Alexis and Alex Hsain, H. and Lee, Younghwan and Strnad, Nicholas A. and Jones, Jacob L. and Hanrahan, Brendan}, year={2022}, month={Jun} }