Abstract:
Plasma processing is a wellestablished technology used in the microelectronics industry for integrated circuit (IC) manufacturing. As the critical dimension of ICs, the length of the gate, continues to shrink, new challenges have arisen for plasma processing of materials.
Advanced electronic devices will incorporate nanoscale components such as nanotubes, nanowires, and nanoparticles that must be fabricated without photolithographic masks. In addition, new areas have emerged in sensors, energy, and medicine that will make it necessary for plasmas to be implemented in schemes for nanomaterials synthesis. To address this issue, our research is focused on developing a new class of plasmas termed “microplasmas” for the synthesis of nanoparticles and other nanoscale materials.
Microplasmas are miniaturized versions of glow discharges that operate stably at atmospheric pressure and contain large concentrations of energetic electrons (110 eV). They are normally formed with directcurrent power between a hollow electrode and a counterelectrode such as a mesh. The salient features of the source, small size (< 1 mm) and highpressure operation, allow novel applications in materials synthesis. Vaporphase precursors can be nonthermally disassociated by the “hot” electrons to produce radical species and homogeneously nucleate nanoparticles in the gas phase. Excessive particle growth and agglomeration is limited by the short residence times in the microplasma, leading to the formation of particles less than 5 nm in size. The synthesis of nanometersized metal particles lends itself to catalytic applications including carbon nanotube and silicon nanowire growth.
We will show that the properties of these onedimensional materials can be precisely controlled by tuning the catalyst size and composition in the microplasma. Recently, we have also coupled microplasmas with liquids or thin films to reduce aqueous metal salt precursors and synthesize nanoparticles as a colloid. In this talk, I will discuss these applications in detail and highlight materials synthesis, characterization, and applications.
Biography:
Mohan Sankaran is currently the George B. Mayer Assistant Professor of Chemical Engineering at Case Western Reserve University (CWRU). He received his Bachelor’s degree in Chemical Engineering from the University of California at Los Angeles in 1998 and his Ph.D. in Chemical Engineering from the California Institute of Technology in 2004. He joined the Department of Chemical Engineering at CWRU in 2005. He has received the Career Award from the National Science Foundation and a Glennan Fellowship from CWRU. His current research interests include microplasmas, nanoparticle synthesis, carbon nanotube and silicon nanowire growth, surfaceenhanced Raman spectroscopy, plasma electrochemistry, and electrostatic charging of materials.