Control of size and density of self-assembled Au droplets via systematic deposition amount control on high-index GaAs type-A surfaces
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概要
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Au droplets as a catalyst can be used to determine the size, density, and configuration of nanowires (NWs) during crystallization at the liquid–solid interface, and the growth direction, cross-sectional shape, and even the quality of the NWs can be controlled by adjusting the substrate index utilized. In this study, the control of the size and density of self-assembled Au droplets is systematically demonstrated via the deposition amount (DA) control between 2 and 12 nm on various GaAs type-A substrates: (711)A, (511)A, (411)A, and (311)A. The self-assembled Au droplets are formed owing to the much higher binding energy between Au adatoms than the energy between Au atoms and substrate atoms based on the Volmer–Weber growth mode, and even up to 12 nm DA, the three-dimensional (3D) island phase (droplets) without coalescence is observed. Within the DA range, the self-assembled Au droplets sensitively respond to the DA variation, which results in over 3 times increment in dimensions along with the corresponding change in density on the two orders of magnitude from ∼10<sup>8</sup>to ∼10<sup>10</sup>. Depending on the index utilized, the high index effect is not obvious owing to weak binding energy between GaAs substrate and Au adatoms and the wide DA range. The results are systematically analyzed using atomic force microscope (AFM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), cross-sectional line profiles, and Fourier filter transform (FFT) power spectra.
- 2014-08-08