| Summary: | 博士 === 淡江大學 === 化學學系博士班 === 96 === Applying Kinetic Monte Carlo (KMC) technique, we investigated the influence of temperature and step-width on the step-flow growth of a (2D+1) semiconductor-like uniform-spacing stepped model with inverse Ehrlich-Schwoebel (iES) barrier (chapter 5, part I) and the effect of deposition rate on the growth pattern of the Alq3 thin film (chapter 6, part II). In the part I, the relation between diffusion length (R) and half of step width (L/2) was established to characterize the transition temperature Tc for switching between the random deposition growth and step-flow growth on surface. When temperature is lower than Tc, the surface growth mode is dominated by random deposition growth. As temperature approaches to Tc, the surface growth mode gradually switches to step-flow growth. However, only when the temperature is much higher than Tc, the random deposition growth is completely replaced by the step-flow growth. It is found that the step-width effect has a profound influence on surface growth mode in the transition region.
In the part II, we successfully investigated the effect of deposition rate on the growth pattern of the Alq3 thin film. In a good agreement with experimental results, our simulation results indicate that there exists a transition growth in terms of the deposition rate corresponding to the transition between the island growth and random deposition growth. In the island growth (deposition rate is lower then 1.1 Å/s) and random deposition growth (deposition rate is higher then 3 Å/s) region, the surface morphology is insensitive to the increasing in the deposition rate. Within the transition growth region (deposition rate is between 1.1 Å/s and 3 Å/s), the homogeneity of film surface improves as the deposition rate increases. Not only the pattern of the island structures becomes blurred but also the inner vacancy ratio and surface roughness remain in low values as the deposition rate increases. From our results, there may exist a deposition rate to optimize the Alq3 film suitable for the luminant devices.
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