This thesis comprises two distinct pieces of work. The first piece involved the fabrication and study of induced one-dimensional hole gas. The second is based on molecular electronics and consisted of the development of nanogaps and measurements of nanocrystals and molecules using the gaps. GaAs/AlGaAs heterostructure was used to create the 1D hole gas. A 2D hole gas can be induced at the GaAs/AlGaAs interface by applying a negative voltage to a surface gate. Changing the gate voltage changes the density of the holes in the 2D system. At low densities, interaction effects become more prominent. The effective mass of holes is about eight times that of electrons in GaAs. Therefore holes are much more sensitive to interaction effects and may exhibit interesting behaviours not seen in electron systems. Unfortunately the quality of wafers were not good enough. Although induced 1D hole devices have been fabricated, they could not give us new insight into physics. For the molecular electronics project a technique was developed to fabricate nanogaps of size 5 nm. These gaps have been used to study molecules and nanocrystals. Both single-particle energy levels and Coulomb charging effects are important in affecting the tunnelling spectra of the nanocrystal devices. Measurements on molecular devices have proved less successful. The molecular systems are very complex, and hold great potential for device applications. The nanogaps developed can be used to measure various nano-elements, the only requirement on the elements being the ability to self-assemble a monolayer on gold surface, which is the way nano-elements are incorporated into the gaps.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:597607 |
| Date | January 2003 |
| Creators | Chin, S. N. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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