Fabrication And Characterization Of Single Electron Transistors Based On One-dimensional ZnO Nanostructures

Zinc oxide (ZnO) nanobelts have attracted tremendous interest due to its properties of wide bandgap (-3.4eV), large exciton binding energy and large surface-to-volume ratio. They have been intensively studied for various photonic and electrical applications. To investigate the electron transport mechanism in ZnO nanobelts, transport of device in few electron regimes could be interesting using a ZnO-nanobelt based single-electron-transistor (SET) device.In this thesis, we fabricated single electron transistors based on single ZnO nanobelt using standard micro-fabrication techniques. The transport properties of the devices were characterized both at room temperature and at low temperature (4.2K). At4.2K, clear coulomb oscillations can be clearly resolved with a period around1V. The main results are as follows:First, single-ZnO-nanobelt based single-electron transistors have been fabricated using micro-fabrication techniques. The micro-fabrication techniques of ZnO nanobelt SETs include electron beam lithography (EBL), UV lithography, thermal evaporation and wire bonding, edc.Second, the transport properties of SET devices were characterized both at room temperature and low temperature (4.2K). At room temperature, the source-drain current increases linearly as the bias voltage increases, indicating a good ohmic contact in the transistors. At4.2K, a Coulomb blockade regime is observed up to a bias voltage of a few millivolts.Third, Clear coulomb oscillations of source-drain current as a function of back gate voltage have been observed at4.2K. The phenomena can be explained well by single charging effects of randomly distributed quantum dots in nanobelts. The size of quantum dots in the nanobelt is about35nm with a charging energy of around lOmeV. The first demonstration of single electron charging effect in ZnO nanobelts will be useful in understanding nanobelt based devices for different applications in future.