| Summary: | 碩士 === 國立交通大學 === 材料科學與工程學系 === 99 === As the miniaturization of electronic components, one-dimensional semiconductor nanomaterials, especially germanium (Ge) nanowires, have attracted great interest for their good quantum confinement effects and high carrier mobility in recently year.
In this thesis, the thermal evaporation was used to synthesize single crystalline Ge nanowires via vapor-liquid-solid (VLS) mechanism under different chamber temperature and total pressure. The best growth parameters for Ge nanowires were 550 °C and 6 torr. The SEM image showed that Ge nanowires were found to grow vertically on silicon (111) substrate. From TEM analysis, the main growth direction of Ge nanowires is [111] and [110].
In addition, we successfully fabricated the Cu3Ge/Ge/Cu3Ge heterostructure by covering copper contact on both sides of Ge nanowire. According to the TEM analysis, the phase of forming copper-germanide was Cu3Ge. The electrical measurement of Ge nanowire, utilized back-gate field effect transistor (FET), reveals that Ge nanowire was p-type channel semiconductor, and the value of hole mobility was 2.279 cm2V-1S-1. Furthermore, the resistivity of Ge was proportional to the diameters. The growth rates of copper-germanide nanowires with different times of annealing were also investigated. With several times of annealing, the gradually growth of copper-germanide nanowire exhibited lower resistivity as the portion of copper-germanide increase. Finally, it was found that the Schottky barrier can be lower by forming copper-germanide/germanium/copper-germanide axial heterostructure nanowire.
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