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Investigation of Dynamics of Nucleation Area during Nanocrystalline Si Film Deposition by Pulsed Laser Ablation

Author: XuWei
Tutor: WangYingLong
School: Hebei University
Course: Optics
Keywords: Pulse laser ablation The average size of Si nanoparticles Nucleation area The gas pressure of Ar The electric field
CLC: TB383.1
Type: Master's thesis
Year: 2008
Downloads: 10
Quote: 0
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Abstract


The nanocrystalline Si films are deposited systematically by pulsed laser ablation (PLA), on the galss or single crystalline (111) Si substrates set under the plume and parallel to its axis in pure Ar gas under the ambient pressure of 10 Pa. Scanning electronic microscope (SEM), x-ray diffraction (XRD) and Raman Scattering spectroscopes (Raman) are used to analyze the surface morphology, component and the microstructure of the samples. The experiment result shows that Si nanoparticles deposited in substrates was in a certain range, and the average size of Si nanoparticles increased firstly then decreased with the parallel distance increasing, the biggest average size of Si nanoparticles is formed at distances 1.3 cm from the target. The nucleation region is simply estimated basing on transport dynamics model and inertia fluid model in pure Ar gas under the ambient pressure of 10 Pa. In the same experiment condition, the ambient gas pressure is changed. The ranges of nucleation area are estimated corresponding different the ambient gas pressure, find out that the location of nucleation area is the nearer to the target, and the range is the wider in the greater ambient gas pressure. In order to determine accurately the range of nucleation area, an electric field was applied perpendicularly on the plume. The transport process of Si nanoparticles was impacted by the electric field. The nanocrystalline Si films are deposited systematically in the different electric field intensity. We investigate the effect of the average size and distribution of Si nanoparticles in the additional electric field, confirmed the mass of Si nanoparticles obtain positive electricity. A series of equations about the transport process of Si nanoparticles is established based on experiment results and theoretics of the nucleation, the nucleation area is exactly determined by the simulation solution. In this work, We suggest the method determined the nucleation area, and educe the result of the nucleation area, which is helpful for both the investigating nucleation mechanism and the understanding transport dynamics of PLA, consequently controlling the grain size of Si nanoparticles.

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CLC: > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials
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