Welcome to Fischer group at the University of Pennsylvania, Department of Materials Science and Engineering. Our primary research covers the novel nanomaterial systems such as carbon nanotubes and semiconductor nanowires. Listed below are highlights of some of our recent publications.



Focused ion beam (FIB) deposited Pt contact on GaN nanowire and its structural and electrical characterization. LEFT TOP: GaN nanowire device fabricated by FIB-Pt deposition, LEFT MIDDLE: TEM sample prepared by FIB milling and lift-off technique by micromanipulator from the FIB-Pt contact area, LEFT BOTTOM: TEM image revealing the structure of FIB-Pt and FIB-induced disorder in GaN nanowire. RIGHT: I-V-T characteristics of FIB-Pt contact for large and small diameter. Back-to-back Schottky junction and Mott variable range hopping conduction explain the behavior. Device fabrication and electrical characterization done by Chang-Yong Nam. Structural and chemical TEM analysis by Douglas Tham. Refer to the publications for details; Nano Letters 5, 2029 (2005) and Advanced Materials 18, 290 (2006)


Graphs showing hydrogen uptake vs pressure for various carbide derived carbons (CDC) and carbon nanotubes: í░Burningí▒ metal carbides in chlorine provides a versatile and growing family of pure, noncrystalline porous carbon in which the average pore size, size distribution and total pore volume can be controlled with great sensitivity by choice of precursor carbide and chlorination reaction conditions (Nature Materials 2, 591 (2003)). These materials show promise to break the hydrogen storage impasse, which blocks development of clean-burning fuel cell cars and trucks. Please refer to our recent publication; í░Tailoring of nanoscale porosity in carbide-derived carbons for hydrogen storageí▒, Y. Gogotsi, R.K. Dash, G. Yushin, T. Yildirim, G. Laudisio, J.E. Fischer, Journal of American Chemical Society 127, 16006 (2005)




Detector images of x-ray scattering of single-wall carbon nanotube (SWNT) fibers. LEFT: As-received SWNT fibers; MIDDLE: SWNT fibers doped by sulfuric acid; RIGHT: Swollen SWNT fibers immersed in sulfuric acid. Measured by Wei Zhou, published in Science 305, 1447 (2004). Please refer to the following press release.