Surface Structure of Self-Organized Sapphire (0001) Substrates with Various Inclined Angles

Abstract

We studied the surface structure of self-organized sapphire (0001) substrates with various inclined angles, using an atomic force microscope (AFM) in UHV. The self-organized surface structure strongly depended on annealing condition, inclined angle and inclined direction. We could successfully produce a highly self-organized step structure by choosing suitable values of these parameters. The surface of the self-organized inclined substrates was characterized by step and terraces. The morphology of step edges depends on the inclined direction of the substrate. In the case of the <100 > inclined direction, the step edges were faceted, and the faceted plane was the {20} plane. On the other hand, in the case of the <110 > inclined direction, the step edges were straight. The distribution of step heights and terrace widths measured from AFM images are presented. The distribution of step heights had peaks corresponding to the unit cell of the sapphire crystal, while the terrace widths followed a normal distribution.