B.S. Physics, Colorado State University, 1983Ph.D. Materials Science and Engineering, MIT, 1992Post-Doc at Sandia National Laboratories, New Mexico, 1992-1994
"Making better materials --> every atom in its place."
Jerry Floro, Professor
My passion in research is to investigate and exploit nanoscale self-assembly and pattern formation in inorganic materials, to enhance properties and develop material functionality. My group employs a range of techniques to synthesize materials, including vapor phase epitaxy and thin film growth, laser processing and rapid solidification, powder processing, and solid-state phase transformations. There is plenty of room at the bottom -- and there is both beauty and mystery there as well.
Bio: I earned my Bachelor's degree in Physics at Colorado State University in 1983, where I did research on modification of surfaces using low energy ion beams, including a project that was likely producing carbon nanotubes before they were "a thing". I then joined the IBM Thomas J. Watson Research Center in Yorktown Heights, NY, where I learned multiple thin film deposition techniques, materials characterization, vacuum technology, and got a great exposure to different sorts of research going on at a very vibrant place. I first heard about Materials Science as a field of study here, and then joined MIT's Ph.D. program in MSE in 1986. My thesis research investigated grain growth in thin films driven by anisotropic surface energy and elastic energy. After finishing in 1992, I began a post doc at Sandia National Labs in Albuquerque, NM. Over the next 14 years, I worked on epitaxial and thin film growth sicence, including quantum dot self-assembly in Group IV semiconductors, the origins of residual stresses in thin films, and strain relaxation mechanisms in III-nitride layers and heterostructures. During this time I helped co-invent the multi-beam optical stress sensor and the light-scattering spectrometer, for real-time, in situ investigation of evolving stress and surface morphology during film growth. In 2006, feeling that my strengths were best suited to academia, I joined the faculty of UVa in the Materials Science and Engineering department. My research currently involves both thin film epitaxial growth and self-assembly, as well as bulk materials processing via rapid solidfication, thermomechanical treatment, powder processing, and/or solid-state phase transformations. These approaches are especially useful for new nanoelectronic, thermoelectric and ferromagnetic materials.
Hartfield-Jefferson Scholars Teaching Prize2012
DOE Materials Science Award for Sustained Outstanding Research in Metallurgy and Ceramics1994
Epitaxial growth and self-assembly of semiconductors and metals
Pattern formation across lengthscales by self-assembly
Thermoelectric materials and thermal transport
Residual stress in thin films
Nanomaterials and nanomanufacturing
Synthesis and thermal transport of eco-friendly Fe-Si-Ge alloys with eutectic/eutectoid microstructure; Mat. Chem. Phys. 207, 67-75 (2018). ABSWade A. Jensen, Naiming Liu, Brian F. Donovan, John A. Tomko, Patrick E. Hopkins, and Jerrold A. Floro
Lengthscale effects on exchange coupling in Co-Pt L10 + L12 nanochessboards; APL Mater. 4, 096103 (2016). ABSEric P. Vetter, Liwei Geng, Priya Ghatwai, Dustin A. Gilbert, Yongmei Jin, William A. Soffa and Jerrold A. Floro
Site-selection of Si1-xGex quantum dots on patterned Si(001) substrates; Appl. Phys. Lett. 109, 193112 (2016). ABSJ. M. Amatya and J. A. Floro
Evolution of microstructure and magnetic properties in Co–Pt alloys bracketing the eutectoid composition; J. Magn. Magn. Mater. 375, 87-95 (2015). ABSP. Ghatwai, E. Vetter, M. Hrdy, W. A. Soffa and J. A. Floro
Highly uniform arrays of epitaxial Ge quantum dots with interdot spacing of 50 nm; J. Mater. Res. 29, 2240-2249 (2014). ABSChristopher J. Duska and Jerrold A. Floro
L1′ ordering: Evidence of L10–L12 hybridization in strained Fe38.5Pd61.5 epitaxial films; Acta Mater. 85, 261-269 (2015). ABSMatthew A. Steiner, Ryan B. Comes, Jerrold A. Floro, William A. Soffa and James M. Fitz-Gerald
Mn solid solutions in self-assembled Ge/Si (001) quantum dot heterostructures, Appl. Phys. Lett. 101, 242407 (2012). ABSJ. Kassim, C. Nolph, M. Jamet, P. Reinke, J. Floro
Epitaxial Si encapsulation of highly misfitting SiC quantum dot arrays formed on Si (001); Appl. Phys. Lett. 104, 013108 (2014). ABSC. W. Petz, D. Yang, A. F. Myers, J. Levy, and J. A. Floro
Misfit dislocation formation in the AlGaN/GaN heterointerface; J. Appl. Phys. 96, 7087-7094 (2004). ABSJ. A. Floro, D. W. Follstaedt, P. Provencio, S. J. Hearne and S. R. Lee
SiGe Island Shape Transitions Induced by Elastic Repulsion; Phys. Rev. Lett. 80, 4717 (1998). ABSJ. A. Floro, G. A. Lucadamo, E. Chason, M. Sinclair, R. D. Twesten and R. Q. Hwang
The Dynamic Competition Between Stress Generation and Relaxation Mechanisms During Coalescence of Volmer-Weber Thin Films, Appl. Phys. 89, 4886 (2001) ABSJ. A. Floro, S. J. Hearne, J. A. Hunter, P. Kotula, E. Chason, S. C. Seel and C. V. Thompson, J.
Introduction to Materials Science and Engineering - Guided Inquiry (MSE 2090)Spring
Introduction to the Crystal and Electronic Structure of Materials (MSE 6010)Fall
Featured Grants & Projects
Science and Schema for Directed Self-Assembly of Heteroepitaxial Quantum Dot Crystals Near the Critical Length Scale
National Science Foundation, Division of Materials Research
This research will develop synthetic quantum dot mesocrystals (QDMCs), which are three-dimensionally periodic arrays of quantum dots epitaxially embedded in a matrix material. These artificial materials, if they can be made, are predicted to have novel and improved properties. The research program described here builds on recent accomplishments in creating two-dimensional arrays of epitaxial Ge quantum dots on Si substrates. These highly periodic, highly uniform arrays, form by directed self-assembly on nanoscale surface templates. The ordered 2D quantum dot arrays will serve as “seed crystals” for the formation of the 3D mesocrystal by additional growth – but no additional templating – of Ge dot layers separated by Si interlayer spacers. The central question is whether heteroepitaxy, especially in the Ge/Si system, can produce 3D arrays of quantum dots at sufficiently small lengthscales, with sufficiently good ordering and uniformity. If this can be achieved, then effects related to quantum confinement, strain-induced bandgap changes, and perhaps even phenomena exploiting wavefunction overlap, will manifest at room temperature, to create useful, artificial electronic structures. The central challenge is to control surface morphology and self-assembly processes close to the intrinsic, limiting lengthscales for heteroepitaxial quantum dot self-assembly, which is about 16 nm for Ge on Si.
Hierarchical Control of Eco-Friendly Fe-Si-Based Alloys for Thermoelectric Applications
We will exploit bulk eutectic + eutectoid transformations using thermomechanical processing techniques to create hierarchically structured materials with improved properties relevant to energy applications, specifically thermoelectrics. Our modus operandi will be to advance fundamental scientific understanding of the phase transformation, while interrogating the effect of structure and chemistry on the transport properties important to the application. We are especially interested in the role of strain and interfacial energy in determining the lengthscales, crystallographic orientations, and topologies of the resulting nanostructures, on the 10-50 nm scale. Simultaneously, the use of isoelectronic alloying is anticipated to provide significant enhancements in the relevant thermal and electronic transport properties; however, these chemical substitutions will also modify and constrain the processing space of the material.
Selection of Lengthscales in Fe-based Nanochessboards to Enhance Exchange-Coupled Ferromagnetism
National Science Foundation, Division of Materials Research
A key strategy for improving the performance of permanent magnets is to create a nanocomposite
structure that includes both magnetically "hard" and "soft" phases. The former has high coercivity, so it
resists switching its polarity, while the latter can have high magnetization. If the phases can be
interleaved on lengthscales of order 10 nm, then exchange-coupling can lead to improved magnetic
energy storage. Exchange-coupled ferromagnetism has been studied in epitaxial thin film systems, which
serve as idealized one-dimensional models, but are not realistic representations for permanent magnets.
Three-dimensional nanocomposite magnets are also heavily studied, but these often have complex
structures and are correspondingly complex to interpret. The unique nanochessboard structure represents
an intermediate case - formed in bulk alloys by a solid-state transformation, chessboards have a highly
regular two-phase microstructure that is well-suited to investigations on the role of lengthscales in
controlling the exchange coupling. The challenge is to select and control the structural lengthscales of the
chessboard in the best range to enhance the coupling.