The surface shape and microstructure of semiconductor thin films, especially nanometer thin films, greatly influence such physical characteristics as the electricity, magnetic and optics nature to the thin films, etc. In this work, we use the fractal dimension and multifractal spectra to study the surface morphology of annealed InGaN/GaN self-assembled quantum dot (SAQD) films. Samples used in this study were grown on (0001)-oriented sapphire (Al2O3) substrates in a vertical low-pressure metalorganic chemical vapor deposition (MOCVD) reactor with a high-speed rotation disk. The fractal dimension and multifractal spectra can be used to describe the influence of different annealing conditions on surface characterization. Fractal analysis reveals that both the average surface roughness and root-mean-square roughness of nanostructure surfaces decreased after thermal annealing. It can be seen that a smoother surface was obtained after an annealing temperature of 800°C, and it implies that the surface roughness of this case is minimum in all tests. The results of this paper also include a mathematical model to describe the observation of fractal and multifractal characteristics in semiconductor nanostructure films.

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