Morphology of Epitaxial Growth of GaAs by a Molecular Beam Method: The Observation of Surface Structures

Homoepitaxial growth of GaAs was studied in situ in an ultrahigh-vacuum high-energy electron diffraction (HEED) system. Two surface structures, GaAs(1̄1̄1̄)−(19)1/2 and GaAs(1̄1̄1̄)−2, were observed during growth. The transition from one surface structure to the other was found to be a function of the deposition rate and the substrate temperature, with the high-temperature structure being the (1̄1̄1̄)−(19)1/2. The film growth morphology was studied by the carbon replication technique. Growth by a step mechanism was observed on a bromine-methanol etched surface while three-dimensional nuclei were observed on a polished or contaminated surface.