@misc{hsain_lee_materano_mittmann_payne_mikolajick_schroeder_parsons_jones_2022, title={Many routes to ferroelectric HfO2: A review of current deposition methods}, volume={40}, ISSN={["1520-8559"]}, url={https://doi.org/10.1116/6.0001317}, DOI={10.1116/6.0001317}, abstractNote={Although 10 years have passed since the initial report of ferroelectricity in hafnia (HfO2), researchers are still intensely fascinated by this material system and the promise it holds for future applications. A wide variety of deposition methods have been deployed to create ferroelectric HfO2 thin films such as atomic layer deposition, chemical solution deposition, and physical vapor deposition methods such as sputtering and pulsed laser deposition. Process and design parameters such as deposition temperature, precursor choice, target source, vacuum level, reactive gases, substrate strain, and many others are often integral in stabilizing the polar orthorhombic phase and ferroelectricity. We examine processing parameters across four main different deposition methods and their effect on film microstructure, phase evolution, defect concentration, and resultant electrical properties. The goal of this review is to integrate the process knowledge collected over the past 10 years in the field of ferroelectric HfO2 into a single comprehensive guide for the design of future HfO2-based ferroelectric materials and devices.}, number={1}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Hsain, Hanan Alexandra and Lee, Younghwan and Materano, Monica and Mittmann, Terence and Payne, Alexis and Mikolajick, Thomas and Schroeder, Uwe and Parsons, Gregory N. and Jones, Jacob L.}, year={2022}, month={Jan} }
 @article{furubayashi_wallace_gonzalez_jahnke_hanrahan_payne_stratis-cullum_gray_liu_rhoads_et al._2021, title={Genetic Tuning of Iron Oxide Nanoparticle Size, Shape, and Surface Properties inMagnetospirillum magneticum}, volume={31}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.202004813}, abstractNote={Abstract}, number={4}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Furubayashi, Maiko and Wallace, Andrea K. and Gonzalez, Lina M. and Jahnke, Justin P. and Hanrahan, Brendan M. and Payne, Alexis L. and Stratis-Cullum, Dimitra N. and Gray, Matthew T. and Liu, Han and Rhoads, Melissa K. and et al.}, year={2021}, month={Jan} }
 @article{thong_payne_li_cheng_jones_wang_2021, title={The origin of chemical inhomogeneity in lead-free potassium sodium niobate ceramic: Competitive chemical reaction during solid-state synthesis}, volume={211}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2021.116833}, abstractNote={Excellent electromechanical properties have been reported in lead-free potassium sodium niobate (KNN)-based piezoelectric ceramics over the past 15 years. However, poor reproducibility of the electromechanical properties of KNN has been a major barrier to industrial development, due to a lack of full understanding of some of the processing aspects. Chemical inhomogeneity is one of the most critical challenges in processing, as the properties of KNN-based ceramics are strongly composition-dependent. In the present study, in-situ temperature-dependent X-ray diffraction and thermogravimetric analysis were employed to investigate the chemical reactions that occur during solid-state synthesis. Chemical homogeneity was found to be sensitive to the competition among reactants during synthesis. The phenomenon can reasonably explain the chemical inhomogeneity in KNN and possibly other lead-free piezoelectric ceramic systems prepared via solid-state synthesis.}, journal={ACTA MATERIALIA}, author={Thong, Hao-Cheng and Payne, Alexis and Li, Jia-Wang and Cheng, Yue-Yu-Shan and Jones, Jacob L. and Wang, Ke}, year={2021}, month={Jun} }
 @article{hanrahan_milesi-brault_leff_payne_liu_guennou_strnad_2021, title={The other model antiferroelectric: PbHfO3 thin films from ALD precursors}, volume={9}, ISSN={["2166-532X"]}, DOI={10.1063/5.0035730}, abstractNote={Antiferroelectric PbHfO3 is grown from atomic layer deposition precursors lead bis(dimethylaminomethylpropanolate) and tetrakis dimethylamino hafnium with H2O and O3 oxidizers in thicknesses from 20 nm to 200 nm at a substrate temperature of 250 °C. X-ray analysis shows an as-grown crystalline PbO phase that diffuses into an amorphous HfO2 matrix upon annealing to form a randomly oriented, orthorhombic PbHfO3 thin film. Electrical characterization reveals characteristic double hysteresis loops with maximum polarizations of around 30 µC/cm2 and transition fields of 350 kV/cm–500 kV/cm depending on the thickness. Temperature-dependent permittivity and polarization testing show a phase transition at 185 °C, most probably to the paraelectric phase, but give no clear evidence for the intermediate phase known from bulk PbHfO3. The energy storage density for the films reaches 16 J/cm3 at 2 MV/cm. A dielectric tunability of 221% is available within 1 V for the thinnest film. These results highlight the unique spectrum of properties available for thin film perovskite antiferroelectrics.}, number={2}, journal={APL MATERIALS}, author={Hanrahan, Brendan and Milesi-Brault, Cosme and Leff, Asher and Payne, Alexis and Liu, Shi and Guennou, Mael and Strnad, Nicholas}, year={2021}, month={Feb} }
 @article{payne_brewer_leff_strnad_jones_hanrahan_2020, title={Dielectric, energy storage, and loss study of antiferroelectric-like Al-doped HfO2 thin films}, volume={117}, ISSN={["1077-3118"]}, DOI={10.1063/5.0029706}, abstractNote={Antiferroelectric thin films have properties ideal for energy storage due to their lower losses compared to their ferroelectric counterparts as well as their robust endurance properties. We fabricated Al-doped HfO2 antiferroelectric thin films via atomic layer deposition at variable thicknesses (20 nm or 50 nm) with varying dopant concentrations (4 at. % or 8 at. %). 50 nm thick 8 at. % Al-doped HfO2 showed a maximum energy storage density of 63 J/cm3 while maintaining an efficiency of 85%. A study comparing these thin films revealed thicker films allowed for higher operating electric fields and thus higher energy storage densities at operating voltage. The loss tangents of the thin films at operating voltage were under 2% over the range of −4 to 4 MV/cm and at frequencies ranging from 500 Hz to 100 kHz. Reliability studies showed the thin films endure up to 106–107 cycles and the breakdown field of the films yielded Weibull moduli greater than 6 for all our thin films. The Weibull modulus provides a measurement of the consistency of the breakdown strength from sample to sample, with higher moduli indicating a more invariable result. These electrical characteristics along with the thin film's cycling endurance and reliability make antiferroelectric-like Al-doped thin films a promising material for energy storage applications.}, number={22}, journal={APPLIED PHYSICS LETTERS}, author={Payne, Alexis and Brewer, Owen and Leff, Asher and Strnad, Nicholas A. and Jones, Jacob L. and Hanrahan, Brendan}, year={2020}, month={Nov} }