This thesis describes a part of the first steps towards DNA sequencing via tunneling current measurement though graphene electrodes. The focus lies in particular on the optimization of the...Show moreThis thesis describes a part of the first steps towards DNA sequencing via tunneling current measurement though graphene electrodes. The focus lies in particular on the optimization of the fabrication and the characterization of the graphene electrodes. Progress has been made in the fabrication of atomically sharp graphene edges supported by a Si/SiO2 substrate with prefabricated contact pads. The optimization of reactive ion etching parameters was analyzed using SEM. However some problems were uncovered with the prefabricated wafers, since the contact pads seem to cause to large a step for the graphene to bridge. This leads to the tearing of graphene after some time when unsupported by a protective top layer. The creation of a tunneling junction with two graphene electrodes using a modified STM device confirmed the previously found results. The same hysteresis in the I-Z curve was observed which is likely due to carbon bonds forming between the two graphene electrodes, however more research is necessary to fully analyze the edge composition of the graphene. Knowing fully what the edge of the graphene looks like on the atomic scale is also important for future steps since this is needed to chemically functionalize the graphene edge and to tunneling current measurements more reproducible. The prefabricated wafers in combination with new sample holders with integrated wiring made to fit the STM also made the use of a backgate possible. However this caused some instability in the tunneling current which needs to be resolved before any valuable measurements can be taken. These measurements should also give us information about the composition of the tunneling junction that is formed.Show less
