The growth behavior and mechanisms of epitaxial lateral overgrowth of GaAs on (001) GaAs substrates were investigated. It was found that the lateral growth exhibited a strong dependence upon the orientation of the seed. Lateral growth was slowest when the aligned seed was oriented in the [100], [110], [010], [¯110], or equivalent, directions. However, it increased sharply when the seed was tilted away from these orientations. Monomolecular growth steps on the surface, with a strong contrast and a high lateral spatial resolution, were successfully observed by using Nomarski differential interference contrast microscopy plus image processing. Their average propagation velocity was estimated to be between 0.003 and 0.03mm/s. It was found that the surface of the epitaxial lateral overgrowth layer was extremely flat at the atomic scale. The experimental results indicated that vertical growth was governed mainly by the propagation of steps that originated from their source. On the other hand, lateral growth was limited by the diffusion of As in Ga solution until (111)- or (001)-type facets appeared at the lateral growth front. The growth then became limited by kinetic processes. It was concluded that substrates of (001)GaAs, as well as (111)GaAs, were suitable for obtaining a very smooth epitaxial lateral overgrowth layer with a large ratio of the lateral growth width to the vertical growth thickness.

S.Zhang, T.Nishinaga: Journal of Crystal Growth, 1990, 99, 292-6