Electronic device fabrication based on conducting polymer nanofibers:

1. Electronic device fabrication based on conducting polymer nanofibers: Motivating undergraduate students towards research in materials science Nicholas J. Pinto (Univ. of Puerto Rico - Humacao),RUI-DMR 0402766 nanofiber Research (2005-2006) • A split-gate field effect transistor was fabricated with regio-regular poly(3hexylthiophene) (P3HT) as the active semiconducting layer. The device worked as a dual input logic AND gate. A significant advantage of this construction is that AND logic devices with multiple inputs can be built using a single P3HT channel with multiple gates which could lead to more compact circuitsa. • A simple method to fabricate under ambient conditions, and within seconds, Schottky nanodiodes using electrospun polyaniline nanofibers and an inorganic n-doped semiconductor was investigated. This device works as a rectifier and the advantage of the current design is the complete exposure of the rectifying nanojunction to the surrounding environment making it attractive in the potential fabrication of low power, supersensitive and rapid response sensors as well (see figures for device construction and characterization)b. Au electrode SiO2 n-doped Si Fig 1. (Right) Schematic of the Schottky nanodiode rectifier. (Left) SEM image of the actual nanofiber at the wafer edge. Fig 2. Current-voltage characteristics at 300 K of the Schottky nanodiode when the positive terminal of Vbias was connected to the gold electrode (blue) and when the positive terminal of Vbias was connected to the doped Si (red) Fig 3. I-V characteristic curves for a Schottky nanodiode when used as a gas sensor and measured in the following sequence: (blue) - as prepared sample measured in vacuum; (purple) - a few seconds after exposure to ammonia vapor; (red) - after 5 hours of pumping to remove ammonia. aDual input AND gate fabricated from a single channel poly(3-hexylthiophene) thin film field effect transistor, N.J. Pinto, R. Pérez, C.H. Mueller, N. Theofylaktos and F.A. Miranda, J. Appl. Phys. 99, 084504 (2006). bElectrospun hybrid organic/inorganic semiconductor Schottky nanodiode N.J. Pinto, R. González, A.T. Johnson, Jr. and A.G. MacDiarmid, Appl. Phys. Lett., in press, (2006).

2. Electronic device fabrication based on conducting polymer nanofibers: Motivating undergraduate students towards research in materials science Nicholas J. Pinto (Univ. of Puerto Rico - Humacao),RUI-DMR 0402766 Education (2005-2006) Outreach (2005-2006) 􀂉 Three undergraduates and one High School Senior participated in research and educational activities. 􀂉 All the participants presented their work at the Junior Technical Meeting in March 2006 and some at the National Conference on Undergraduate Research (NCUR) in April 2006. 􀂉 Students, Rosana González is seeking out grad schools, Raúl Pérez is at UPENN in their summer SUNFEST program and Rut Rivera who graduated from High School has enrolled as a freshman at UPR-Humacao and will continue to work with Pinto in the Fall. 􀂉Pinto participated in a one week NSF-PREM sponsored workshop on nanoscience and nanotechnology for High School students. 􀂉 Pinto visited several local High Schools during the last year to expose students to the program of study and of research opportunities available in the Physics Department at UPR-Humacao. 􀂉 The American Institute of Physics (July 2005, AIP Pub. # R151.40) ranked the Physics Department at UPR-Humacao 18 out of 511 Universities in the US that graduated 10 or more Physics Bachelor’s degrees in 2001, 2002 and 2003. Pinto helping a High School student make electrical connections to electrospun polyaniline nanofibers at the workshop on nanoscience and nanotechnology Rut and Rosana present their poster at the NCUR 2006 meeting in Asheville, NC in April 2006