Hamers Group Research Projects
Developing and understanding new chemical routes to controlling surface chemistry .
Silicon, germanium, and diamond all have the same crystal structure and adopt very similar arrangements of atoms at their surfaces. Many new and emerging properties of semiconductor materials on both "macro" and "nano" scales depend on the ability to interface semiconductors with organic and/or biological materials. Our group has a strong emphasis on developing and characterizing new methods for functionalizing semiconductor surfaces. Most of our recent work is targeted toward development of new "wet-chemical" photochemical and electrochemical functionalization reactions. We have a full complement of surface analytical methods in our labs iincluding X-ray photoelectron spectroscopy (XPS), Ultraviolet photoelectron spectroscopy (UPS), monolayer-sensitivity Fourier-transform infrared spectroscopy (FTIR) methods, electrochemical methods, scanning electron microsopy, and atomic force /scanning tunneling microscopies. We have recently developed an excellent method for functionalizing surfaces of covalent semiconductors that is based upon a unique photochemical process; this method is quite general and provides a direct way to link semiconductors to a wide range of organic and biological materials.
Current materials of interest include carbon (including nanotubes and nanofibers), wide-bandgap semiconductors such as GaN and TiO2, and silicon. Carbon-based materials are of particularly great interest because these materials are extremely stable, able to withstand harsh chemical, electrochemical, and thermal conditions. We have recently developed a number of novel photochemical and electrochemical methods for functionalizing surfaces of silicon, diamond, carbon-based nanomaterials, and germanium.
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Kevin Metz at the helm of the XPS/UPS sytem. |
Some recent papers: (numbers refer to complete publications list)
Diamond and Amorphous Carbon:
B.M. Nichols, K.M. Metz, K.-Y. Tse, J.E. Butler, J.N. Russell, Jr., and R.J. Hamers, "Electrical Bias-dependent Photochemical Functionalization of Diamond Surfaces", Journal of Physical Chemistry B, accepted 6/06.
Beth M. Nichols, John N. Russell, Jr., James E. Butler, and Robert J. Hamers, "Photochemical Functionalization of Hydrogen-terminated Diamond Surfaces: A Structural and Mechanistic Study", Journal of Physical Chemistry B, 109, 20938-20947 (2005). Link to paper Link to supporting Information
Kiu-Yuen Tse, Beth M. Nichols, Wensha Yang, James E. Butler, John N. Russell, Jr., and Robert J. Hamers, :"Electrical properties of diamond surfaces functionalized with molecular monolayers" , J. Phys. Chem. B, 109, 8523-8532 (2005). Link to paper
Tami Lasseter Clare, Brian H. Clare, Beth M. Nichols, Nicholas L. Abbott, and Robert J. Hamers, "Functional Monolayers for Improved Resistance to Protein Adsorption: Oligo(ethylene glycol) Modified Silicon and Diamond Surfaces", Langmuir, 21, 6344-6355 (2005).
Wensha Yang, Sarah E. Baker James E. Butler, Chang-soo Lee, John N. Russell, Jr, Lu Shang, Bin Sun, Robert J. Hamers, "Electrically Addressable Biomolecular Functionalization of Conductive Nanocrystalline Diamond Thin Films", Chemistry of Materials, 17, 938-940 (2005).
Tami L. Lasseter, Brian H. Clare, Nicholas L. Abbott, and Robert J. Hamers, "Covalently Modified Silicon and Diamond Surfaces: Resistance to Non-Specific Protein Adsorption and Optimization for Biosensing", J. Am. Chem. Soc., 126, 10220-10221 (2004).
Wensha Yang, James E. Butler, John N. Russell, Jr., and Robert J. Hamers, "Interfacial Electrical Properties of DNA-modified Diamond Thin Films: Intrinsic Response and Hybridization-Induced Field Effects", Langmuir, 20, 6778-6784 (2004)..
Wensha Yang, James E. Butler, Wei Cai, John Carlisle, Dieter Gruen, Tanya Knickerbocker, John N. Russell, Jr., Lloyd M. Smith, and Robert J. Hamers, "DNA-modified nanocrystalline diamond films as stable, biologically active substrates", Nature Materials, 1, 253-257 (2002).
Todd Strother, Tanya Knickerbocker, John N. Russell, Jr., James E. Butler, Lloyd M. Smith, and Robert J. Hamers, "Photochemical Functionalization of Diamond Films", Langmuir, 18, 968-971 (2002).
Carbon Nanofibers:
Sarah E. Baker, Kiu-Yuen Tse, Eve Hindin, Beth M. Nichols, Tami Lasseter Clare, and Robert J. Hamers, "Covalent Functionalization for Biomolecular Recognition on Vertically Aligned Carbon Nanofibers", Chemistry of Materials, 17, 4971-4978 (2005).
Sarah E. Baker, Kiu-Yuen Tse, Chang-Soo Lee, and Robert J. Hamers, "Fabrication and Characterization of Vertically Aligned Carbon Nanofiber Electrodes for Biosensing Applications", Diamond and Related Materials, 15, 433-439 (2006). Link to paper.
Chang-Soo Lee, Sarah E. Baker, Matthew S. Marcus, Wensha Yang, Mark A. Eriksson, and Robert J. Hamers, "Electrically Addressable Biomolecular Functionalization of Carbon Nanotube and Carbon Nanofiber Electrodes", Nano Letters, 4, 1713-1716 (2004). Paper Supplementary Information
Silicon and Silicon Nanowires
Jeremy A. Streifer, Heesuk Kim, Beth M. Nichols, and Robert J. Hamers,"Covalent functionalization and hybridization of DNA-modified silicon nanowires", Nanotechnology,16, 1868-1873 (2005).
Robert J. Hamers, James E. Butler, Tami Lasseter, Beth M. Nichols, John N. Russell, Jr., Kiu-Yuen Tse, and Wensha Yang, "Molecuar and Biomolecular Monolayers on Diamond as an Interface to Biology", Diamond & Related Materials, accepted 9/04.