High Pressure Chemistry in Confined Geometries for Photonics and More



  • We use chemistry to develop new ways to organize inorganic semiconductor, metallic, and molecular materials in 1-d templates at dimensions down to the nanoscale.

    The controlled hierarchical assembly of individual nanoscale elements such as quantum dots and nanowires into high-quality, precisely designed functional materials and devices provides a compelling challenge in nanoscience. We use chemistry to develop new ways to organize inorganic semiconductor, metallic, and molecular materials in 1-d templates at dimensions down to the nanoscale. The resulting 1-d structures are natural conduits for light, electrons, and flowing gases or fluids, which can be manipulated and coupled together inside them in many useful ways over centimeters to meters long length scales.

    Major research focuses are developing high pressure chemistry to make atomically smooth, geometrically perfect structures with high materials quality that have excellent optical and electronic properties and organizing these structures with increasing sophistication in templates.

    Silica microstructured optical fiber nanotemplates can have arrays of pores designed in virtually any desired pattern (see MOF figure). These meters long pores can have diameters from microns to nanometers in one template and can be precisely spatially arranged relative to each within nanometers. Our research has demonstrated that by treating these ultra-high aspect ratio pores as high pressure chemical reactors we can fill them void free (11) with unary (12) and compound semiconductors (13) (26) (see cross-sectional SEM figure). The resulting near atomically smooth (14) nano or microscale diameter semiconductor wires and tubes are much longer and more geometrically perfect than structures typically made by conventional nanofabrication methods. They have the further advantage that they are embedded in a macroscale size, rugged, functional template that makes them easy to handle and allows light, electricity and/or flowing fluids to be readily coupled into them. Major research focuses are developing high pressure chemistry to make atomically smooth, geometrically perfect structures with high materials quality that have excellent optical and electronic properties and organizing these structures with increasing sophistication in templates.

    Layer by layer deposition in the pores can also form very uniform doped semiconductor homo and heterojunctions (see junction figures) (15, 27). The "outside-in" nature of this template-based approach to annular junctions contrasts with the usual approach of depositing on the exterior of nanowires. Patterning a junction adjacent to a central silica core allows for a unique light coupling scheme that overcomes the difficulties in transferring light from low refractive index silica to high index silicon without a large impedance mismatch (15).

    The extreme aspect ratios, spatial organization, and geometric perfection of these wires and junctions make them of interest for a wide range of applications

    The extreme aspect ratios, spatial organization, and geometric perfection of these wires and junctions make them of interest for a wide range of applications (30), including high speed optoelectronic fiber devices (15), nanofluidics, all optical signal processing (29), chemical sensors (16), optical waveguides (17), high quality factor resonators (18), subwavelength high resolution infrared imaging (19), non-linear optics (20), solar cells (27), confined 1-d physics, and fiber lasers. To pursue these applications, group members often work with our collaborators, including the Southampton University ORC in the UK, and the Gopalan group at Penn State. Templated high pressure deposition is practical and scalable in view of the small volumes of reactants employed. See the in the news for some outside perspectives on applications.

    In addition to inorganic solids, self-assembled molecules (16, 21) can be layered, patterned, and characterized via Raman spectroscopy within the arrays of pores in fiber nanotemplates to provide further flexibility in hierarchically organizing complex materials.

    Nearly every aspect of the pathway from molecular precursor to reaction product, including reactant flow, surface chemistry, chemical kinetics and thermodynamics, and nucleation and growth, differs from that under conventional conditions.

    The behavior of molecules compressed to high pressures and constrained to the small dimensions of the nano/microreactors is dramatically altered. Nearly every aspect of the pathway from molecular precursor to reaction product, including reactant flow, surface chemistry, chemical kinetics and thermodynamics, and nucleation and growth, differs from that under conventional conditions (11), giving a rich variety of chemical phenomena to investigate. There are kinetic/flow effects that increase reactant concentration (22). Supersonic flow can form nanonozzles (22). The width of the "stagnant" layer of precursor present near the reaction interface at low reaction pressures in large volume reactors is greatly reduced. Competition between single crystal growth and deposition on pore walls must be controlled (23). The nm long mean free paths and associated high molecular collision frequency in silane precursor allows for reaction at low enough temperatures for templated growth of nanowires of hydrogenated amorphous silicon (11), a material that is useful for non-linear optics and solar cells. Dopant molecule reaction kinetics and thermodynamics has to be understood to allow for carefully regulated impurity doping and formation of junctions with a built-in potential (15). We have also shown that the remarkable transport properties of pressure driven precursors allows for the formation of nanopores in semiconductor wires many centimeters long (13). We use a combination of experiment and theory/modeling to determine how chemistry is altered under the unusual reaction conditions employed (11, 12, 22, 23). Exploiting these differences to make materials and structures is central to our research.


  • Selected Publications

    • (1) Badding, J. V. High-pressure synthesis, characterization, and tuning of solid-state materials. Annual Review of Materials Science 28, 631 (1998).
    • (2) Parker, L. J., Atou, T. & Badding, J. V. Transition element-like chemistry for potassium under pressure. Science 273, 95 (1996).
    • (3) Atou, T., Hasegawa, M., Parker, L. J. & Badding, J. V. Unusual Chemical Behavior for Potassium under Pressure: Potassium-Silver Compounds. Journal of the American Chemical Society 118, 12104 (1996).
    • (4) Badding, J.V., Lueking, A.L., Reversible High Pressure sp2-sp3 Transformations in Carbon, Phase Transitions, 80, 1033 (2007)
    • (5) Miller, E. D., Nesting, D. C. & Badding, J. V. Quenchable Transparent Phase of Carbon. Chemistry of Materials 9, 18 (1997).
    • (6) Jackson, B. R., Trout, C. C. & Badding, J. V. UV Raman Analysis of the C:H Network Formed by Compression of Benzene. Chemistry of Materials 15, 1820 (2003).
    • (7) Ravindran, T. R. & Badding, J. V. Ultraviolet Raman analysis of the formation of diamond from C60. Solid State Communications 121, 391 (2002).
    • (8) Badding, J. V. Solid-state carbon nitrides. Advanced Materials 9, 877 (1997).
    • (9) Ravindran, T. R., Jackson, B. R. & Badding, J. V. UV Raman Spectroscopy of Single-Walled Carbon Nanotubes. Chemistry of Materials 13, 4187 (2001).
    • (10) Polvani, D. A., Meng, J. F., Shekar, N. V. C., Sharp, J. & Badding, J. V. Large Improvement in Thermoelectric Properties in Pressure-Tuned p-Type Sb1.5Bi0.5Te3. Chemistry of Materials 13, 2068 (2001).
    • (11) Baril, N.F, He, R., Day, T.D., Sparks, J.R., Keshavarzi, B, , Krishnamurthi, M, Borhan, A, Gopalan, V, Peacock, A.C, Heal, N, . Sazio, P.J.A., and Badding, J. V. Confined High-Pressure Chemical Deposition of Hydrogenated Amorphous Silicon, Journal of the American Chemical Society, 134, 19-22 (2012).
    • (12) Sazio, P. J. A., Amezcua-Correa, A., Finlayson, C. E., Hayes, J. R., Scheidemantel, T. J., Baril, N. F., Jackson, B. R., Won, D.-J., Zhang, F., Margine, E. R., Gopalan, V., Crespi, V. H. & Badding, J. V. Microstructured Optical Fibers as High-Pressure Microfluidic Reactors. Science 311, 1583 (2006).
    • (13) Sparks, J.R., He, R., Healy, N., Krishnamurthi, M, Peacock, A.M., Sazio, P.J.A., Gopalan, V. Badding, J.V. Zinc Selenide Optical Fibers, Advanced Materials, 23, 1647 (2011).
    • (14) Healy, N., Lagonigro, L., Sparks, J.R., Boden, S., Sazio, P.J.A., Badding, J.V., and Peacock, A.C., Polycrystalline silicon optical fibers with atomically smooth surfaces, Optics Letters, 36, 12480-2482 (2011).
    • (15) He, R.,Sazio, P.J.A., Peacock, A.C, Heal, N., Sparks, J.R., Krishnamurthi, M, Gopalan, V, and Badding, J. V., Integration of GHz Bandwidth Semiconductor Devices inside Microstructured Optical Fibres, Nature Photonics, 6, 174-179 (2012).
    • (16) Calkins, J.A., Peacock, A.C, Sazio, P. J. A., Allara, D.L., and Badding, J. V. Spontaneous Waveguide Raman Spectroscopy of Self-Assembled Monolayers in Silica Micropores, Langmuir, 27, 630 (2011).
    • (17) Mehta, P., Krishanmurthi, M., Healy, N., Baril, N. F., Sparks, J., Sazio, P. J. A., Gopalan,V., Badding, J. V. and Peacock, A. C. Mid-infrared transmission properties of amorphous germanium optical fibers, Applied Physics Letters, 97, 071117 (2010).
    • (18) Vukovic, N, Healy, N, Horak, P., Sparks, J.R., Sazio, P.J.A., Badding, J.V., and, Peacock, A.C., Ultra-smooth microcylindrical resonators fabricated from silicon optical fibers, Applied Physics Letters, 99. 03117 (2011).
    • (19) Krishnamurthi, M, Sparks, J.R., He, R.,Temkyh, I., Baril, N.F., Liu, Z., Sazio, P.J.A., Badding, J. V., and Gopalan, V, An Array of Tapered Semiconductor Waveguides in a Fiber for Infrared Image Transfer and Magnification Optics Express, 20, 4168-4175 (2012).
    • (20) Mehta, P., Healy, N., Baril,N. F., Sazio, P. J. A., Badding, J. V. and Peacock, A. C. Nonlinear transmission properties of hydrogenated amorphous silicon core optical fibers, Optics Express, 18, 16826 (2010).
    • (21) Danisman, M.F, Calkins, J.A. Sazio, P.J.A., Allara, D.A., Badding, J.V. Organosilane Self Assembled Monolayer Growth from Supercritical Carbon Dioxide in Microstructured Optical Fiber Capillary Arrays, Langmuir, 24, 3636 (2008).
    • (22) Baril, N. F., Keshavarzi, B., Sparks, J. Krishnamurthi, M., Temnykh, I., Sazio, P. J. A., Peacock, A. C., Borhan, A., Gopalan, V., Badding, J. V. High Pressure Chemical Deposition for Void-Free Filling of Extreme Aspect Ratio Templates, Advanced Materials, 22, 4605 (2010).
    • (23) Jackson, B.R., Sazio, P.J., Badding,J.V., Single Crystal Silicon Wires Integrated into Microstructured Optical Fiber Templates, Advanced Materials, 20, 1135 (2008).
    • (24) Borkar, S., Gu, B., Dirmyer, M., Delicado, R., Sen, A., Jackson, B. R. & Badding, J. V. Polytetrafluoroethylene nano/microfibers by jet blowing. Polymer 47, 8337-8343 (2006).
    • (25) Ainslie, K. M., Bachelder, E. M., Borkar, S., Zahr, A. S., Sen, A., Badding, J. V. & Pishko, M. V.Albumin Adsorption and Cell Adhesion on Nanofibrous Polytetrafluoroethylene (nPTFE). Langmuir, 23, 747-754 (2007).
    • (26) Sparks, J.R., He, R., Healy, N., Chaudhuri, S., Peacock, A.C., Sazio, P.J.A., and Badding, J. V., Conformal Coating by High Pressure Chemical Deposition for Patterned Microwires of II-VI Semiconductors, Advanced Functional Materials 10.1002/adfm.201202224.
    • (27) He, R., Day, T.D., Krishnamurthi, M., Sparks, J.R., Sazio, P.J.A., Gopalan, V., and Badding, J. V., Silicon p-i-n Junction Fibers, Advanced Materials 10.1002/adma.201203879.
    • (28) Liu, X., Tang, Y., Xu, E., Fitzgibbons, T., Larsen, G., Gutierrez, H., Tseng, H.-H., Yu, M.-S., Tsao, C.-S., Badding, J., Crespi, V., Lueking, A., Evidence for Ambient-Temperature Reversible Catalytic Hydrogenation in Pt-doped Carbons, Nano Letters 10.1021/nl303673z.
    • (29) Mehta, P., Healy, N., Day, T.D., Badding, J. V., and Peacock, A. C. Ultrafast wavelength conversion via cross-phase modulation in hydrogenated amorphous silicon optical fibers, Optics Express 20, 26110-26116 (2012).
    • (30) Sparks, J.R., Sazio, P.J.A., Gopalan, V., Badding, J. V., Templated Chemically Deposited Semiconductor Optical Fiber Materials, Annual Review of Materials Research, 0.1146/annurev-matsci-073012-125958.