Investigation into the crystal structure of gallium-selenide nanowires

Gallium-selenide films grown by heteroepitaxy on silicon substrates exhibit two primary growth structures: layered GaSe and defected zinc-blende Ga2Se3. The latter is seen when growing on the (100) surface of silicon, and an emergent structure of nanowires is observed. My project for the ten week summer program at the University of Washington physics department was to investigate the nanowire structure, attempting to determine the atomic configuration by examining the total energy of the different theorized structures. I worked under Prof. Marjorie Olmstead on this project, and the gallium-selenide results were from experiments by Taisuke Ohta. I also had help from Prof. Fumio Ohuchi, Prof. John Rehr, Dr. Fernando Vila,, and Micah Prange. It was decided that I should use a software package called VASP (the Vienna Ab-initio Simulation Package) to examine the gallium-selenide system. This software had to be purchased first, which took several weeks, so in the meantime I worked with a program called FEFF, examining the local density of states of the silicon substrate. At the time of writing, this project is still in progress.