GROWTH-PROCESS OF III-V-COMPOUND SEMICONDUCTORS BY MIGRATION-ENHANCED EPITAXY

The growth mechanism of GaAs and AlGaAs in migration-enhanced epitaxy is investigated by RHEED observation and optical scattering measurements. The available Ga site density on a (2 × 4) reconstructed GaAs (001) surface is much less than the ideal density due to a missing As-dimer array structure. The layer-by-layer growth of GaAs by migration-enhanced epitaxy proceeds by repeated formation and annihilation of small Ga droplets. The growth process is also investigated by studying growth on singular and vicinal (001) GaAs planes. The observed step-flow growth is explained by considering the different chemical characteristics of the steps along the [110] and [110] directions. The results are compared with those of other growth methods such as molecular beam epitaxy and metalorganic vapor phase epitaxy. © 1990.