HIGH-RESOLUTION TRANSMISSION ELECTRON-MICROSCOPY CHARACTERIZATION OF III-V COMPOUNDS ON SI GROWN BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

Misfit dislocations in GaAs, AlGaAs and GaP layers grown on Si substrates by metalorganic chemical vapor deposition are characterized by high-resolution transmission electron microscopy (HRTEM). The lattice mismatch of GaAs on Si is completely relaxed by the misfit dislocations. The Burgers vector of the misfit dislocation is greatly affected by the growth mode at the initial stage of the growth. Lomer misfit dislocations are dominant when the epitaxial layer grows three-dimensionally at the initial stage (GaAs on Si and AlGaAs on Si), and 60 degrees dislocations are dominant when the epitaxial layer grows two-dimensionally at the initial stage (GaP on Si). A mechanism for Lomer misfit dislocation generation in the case of three-dimensional growth is proposed.