HIGH-RESOLUTION TRANSMISSION ELECTRON-MICROSCOPY STUDY OF A GAAS/SI HETEROSTRUCTURE GROWN BY CHEMICAL BEAM EPITAXY

We have successfully grown epitaxial GaAs on a Si(001) substrate by chemical beam epitaxy (CBE). Misfit dislocations and stacking faults in the GaAs/Si interface have been analyzed by high resolution transmission electron microscopy (HRTEM). The results indicate that the lattice mismatch between GaAs epilayer and Si substrate is completely accommodated mostly by 90-degrees pure-edge misfit dislocations, and partly by 60-degrees mixed misfit dislocations and stacking faults. Residual amorphous patches, presumably of SiO2, on the substrate surface appear to act as nucleation sites for stacking faults. Areas of thin amorphous layer on the substrate do not seem to prevent the epitaxial growth of GaAs on the Si substrate.