A thesis submitted November 2015 for the degree of Doctor of Philosophy and defended February 2, 2016.
The PhD School of Science
Faculty of Science
Niels Bohr Institute, Center for Quantum Devices & Nano Science Center, University of Copenhagen
Thomas Sand Jespersen
Raman Spectroscopy of InAs based Nanowires & Electronic Characterization of Heterostructure InAs/GaInAs Nanowires
The work presented in this thesis represents two main topics. The first one, which covers a bigger volume of the thesis, is mainly about Raman spectroscopy on individual InAs based nanowires. The second part presents electronic characterization of heterostructure InAs/GaInAs nanowires.
Raman spectroscopy measurements on InAs based nanowires include several topics. Firstly, we use polarized Raman spectroscopy for determining the crystal orientation of the nanowires based on conventional Raman selection rules. We studied the effect of the high power laser irradiation on the nanowire, and its relation to the nanowire surface facets. We present controlled oxidation experiments on InAs nanowires enabled by fabrication of micro-trenches in the substrate and the electronic properties of the oxidized nanowire were also studied. Finally, we present an attempt to detect the LO phonon-plasmon coupled modes.
In the last chapter of this thesis we present a study on electrical characterization of InAs/GaInAs heterostructure nanowires. First, we performed selective etching experiments in order to locate the barriers. Second, the barriers were probed electrically by performing thermally activated transport measurements.