Electric force microscopy of one dimensional nanostructures

• Main Author: Bell, Kimberley F.
• Published: Swansea University 2010
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.752222

As the limitations of current technology and the possibility of scaling down of technology becomes ever more apparent the drive for smaller, faster, cheaper and more sensitive devices gains momentum. Recent literature reports new and exciting possibilities with zinc oxide based one-dimensional nanomaterials rather than the popular carbon nanotubes. The attractiveness of these one-dimensional nanomaterials is the increased surface to volume ratios and the ability of this increased surface area to exhibit sensitivity to a range of gases by altering the conductivity upon absorption of molecules on the surface. The work in this thesis demonstrated the effectiveness of the electric force microscopy technique in imaging conducting and semi-conducting samples. The technique is extremely useful in charging nanomaterials and imaging the sample discharging. This technique allows for the imaging of nanomaterials with varying applied tip bias and the results allowed the determination of a method to calculate the dielectric constant of one dimensional nanomaterials by examining the phase data. The second part of this thesis illustrates the intriguing nature of zinc oxide one dimensional nanomaterials by exploring the gas sensing capabilities of single nanowire devices. The sensitivity observed is mostly likely due to the absorption of electron donating molecules to the surface of the nanowire and hence donating charge carriers into the bulk increasing the conduction. This sensitivity can also be due to electron withdrawing molecules being absorbed onto the surface of the nanowire which reduces the conduction.