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Electric Charging and Nanostructure Formation in Polymeric Films using Combined Amplitude-Modulated Atomic Force Microscopy Assisted Electrostaitc Nanolithography and Electric Force Microscopy

Reagan, Michael A.

Abstract Details

2009, Master of Science in Polymer Engineering, University of Akron, Polymer Engineering.

Chemically induced rearrangements of amphifunctional molecules have been demonstrated using strong nonuniform electric fields (108-1010 V/m) induced in the vicinity of nanoscale asperities. Electrostatic interactions utilizing these rearrangements of alkylthiolates assembled on Au(111) result in the nanopatterning of raised nanostructure (1.5 - 9 nm high, 15 - 100 nm wide) arrays on a second time scale by manipulating an atomic force microscope (AFM) tip above the monolayer. It is suspected that, as a result of the oxidative cleavage initiated by a weak bias of the tip, the S end of the alkylthiolate chain carrying a sulfenium cation is attracted to the (lifting) tip, forming bi- and higher-layer structures in the vicinity of the tip apex. Stabilization of the multiple-layered structures is accomplished via mutual attraction and entanglement of hydrocarbon chains. The rearrangements suggest a novel and general approach for nanoscale architecture in self-assembled systems.

Water condensation is shown to have a major influence on electric charge transport and nanostructure formation in polymer-, and semiconductor-thin-film surfaces in the proximity of a biased Atomic Force Microscope (AFM) tip. The water forms a meniscus bridge between the AFM tip and the surface to form a three-component system comprised of the AFM tip, water meniscus, and the surface. The associated electric field in the meniscus is spatially non-uniform and has a magnitude of the order of 108-1010 V/m. An intensive experimental analysis of the input and output electric currents in the AFM tip/water meniscus/surface system, performed at various relative humidity levels between 10 and 60%, indicates that the magnitude of the output current, drained from surface, reaches values as large as several µ¿¿¿¿A which exceeds the input current, injected via the AFM tip (0.01-10 nA), by at least an order of magnitude. This effect is particularly evident when the relative humidity is greater than 20-25%, suggesting that the water meniscus is ionized by the strong electric field to produce electrons. Since the method described here for nanopatterning is applicable for materials with significantly different physical, electronic, and optical properties, and is dependent largely on the ambient humidity level and the strength of the electric field, it is suggested that the method may be extended to a variety of other materials.

We utilized a hybrid technique, based on lithography exploiting atomic force microscope tip manipulation combined with modified Electric Force Microscopy to study surface electric charging (deposition and evolution) of poly-methyl methacryalate (PMMA) and polystyrene (PS) films. Two distinct regimes were observed: 1) Mass transport regime related to electric breakdown due to the negative surface charging followed by stable nanostructure formation (negative tip bias); 2) Occasional - to - no feature formation regime attributed to elastic deformation of polymer surface followed by the surface relaxation in the case of positive surface charging (positive tip bias).

Sergei Lyuksyutov, PhD (Advisor)
Erol Sancaktar, PhD (Advisor)
92 p.

Recommended Citations

Citations

  • Reagan, M. A. (2009). Electric Charging and Nanostructure Formation in Polymeric Films using Combined Amplitude-Modulated Atomic Force Microscopy Assisted Electrostaitc Nanolithography and Electric Force Microscopy [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1239637956

    APA Style (7th edition)

  • Reagan, Michael. Electric Charging and Nanostructure Formation in Polymeric Films using Combined Amplitude-Modulated Atomic Force Microscopy Assisted Electrostaitc Nanolithography and Electric Force Microscopy. 2009. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1239637956.

    MLA Style (8th edition)

  • Reagan, Michael. "Electric Charging and Nanostructure Formation in Polymeric Films using Combined Amplitude-Modulated Atomic Force Microscopy Assisted Electrostaitc Nanolithography and Electric Force Microscopy." Master's thesis, University of Akron, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1239637956

    Chicago Manual of Style (17th edition)