Introduction
Research in our laboratory is in the interdisciplinary field of nanoscience and nanotechnology, with an emphasis on the development of micro-/nano- devices for analytical, biomedical, electronics, and energy conversion/utilization applications. Our research covers (1) nanomaterials growth, (2) device fabrication/characterization, and (3) applications development. These projects are in close collaboration with academia, industry, and government labs.
Nanomaterials Growth
Our nanomaterials synthesis work is focused on preparing high-aspect ratio nanowires (NWs). A major effort is on exploring new methods to grow nanowires deterministically on solid substrates with controlled diameter, length, and orientation (particularly in free-standing vertical orientation) for device applications. The nanowire materials include carbon nanotubes (CNTs), carbon nanofibers (CNFs), semiconducting inorganic crystalline nanowires (s-NWs), and metallic nanowires (m-NWs). The methods include thermal chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), and electrochemical deposition. Another effort is on large-quantity synthesis of NWs with hydrothermal method. NW materials such as ZnO, Bi2Te3, MnO2, etc. have been prepared for various applications.
Fig. 1 Materials Synthesis |
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Vertically aligned CNF array by PECVD |
PECVD reactor for CNT/CNF growth | ZnO nanowires by hydrothermal synthesis |
Device Fabrication/Characterization
We employ conventional solid-state micro-/nano- fabrication techniques including lithography, CVD/PVD, plasma and wet chemical etching, sputtering, and chemical mechanical polishing. In addition, nonconventional methods such as soft-lithography, imprinting, templating, electrochemical etching/deposition, and chemical functionalization are investigated. Most fabrication processes employ a bottom-up method using massive arrays of vertically aligned CNTs and NWs on patterned substrates. The electronic, physical, and chemical properties and device performance are studied with electrochemistry, I-V measurements, optical spectroscopy, electron microscopy, and scanning probe microscopy. For biomaterials and biomedical devices, experiments involving molecular biochemistry, cell/tissue culture, and in-vivo animal experiments are carried in our lab or through collaborations.
Fig. 2 Device Fabrication |
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30 dies on a 4” wafer |
3x3 microarray on each die |
CNF nanoarray |
Nanoelectrode array |
Fig. 3 Electrochemical characterization |
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