The binding energies of a copper adatom and its cluster to the copper (111) surface have been calculated. The binding energy EN of an N-adatom cluster can be roughly written as EN = 3NE1 + mE2, where 3N1 is the binding energy of a single adatom to the (111) surface and m is the number of bonds within the cluster and E2is the binding energy of the bond within the cluster. It was found that E1 = 0.87 eV and E2 = 0.40 – 0.32 eV. The activation energies of motion of these adatom clusters and vacancies and di vacancies on copper (111) and (100) surfaces have been calculated by use of n-body embedded atom potentials and molecular dynamics.

Highly lattice mismatched InGaAs epitaxial layers on GaAs substrates were grown by low pressure MOCVD technique in order to improve surface morphology and interfacial quality. Four different structures were grown at a low temperature of 435°C. A thick In0.65Ga0.35As layer with a thickness of 1.6 μ m was grown directly on GaAs as a reference, while a similar InGaAs film was grown on a linearly graded compositional InxGA1-xAs buffer layer. Two additional In0.85Ga0.15As buffer layers were similarly grown on GaAs by embedding a thin metal film of either In or Ga at the heterointerface. Contrary to the reference sample and the sample with a graded buffer layer, the samples embedded with the metal films show no cross-hatch pattern and exhibit mirror-like surfaces. Cross-sectional high resolution TEM analysis for the samples with a metallic prelayer indicates that the misfit is relieved mainly by 90° perfect dislocations uniformly distributed near the interface. Hall effect measurements also suggest that the defect densities of these two samples are significantly lower than that of the reference sample.

GaAs-AlAs heterostructures have been grown on a GaAs substrate in a low pressure MOCVD reactor. After the C doped AlAs layer was deposited on a GaAs substrate, the undoped GaAs cap layer was grown with a thickness of 150 Å. The sample was exposed to hot water vapor mixed with N2 in a sealed furnace at 400 °C for 15 min. After the thermal oxidation, the sample was characterized by DCXRD, SIMS, AES, XPS, and TEM. The analyses indicate that the aluminum oxide layer is formed from C doped AlAs layer with stable microcrystalline Al2O3, and that the upper part of GaAs cap layer exposed to water vapor is modified to gallium oxide and arsenic oxide, while the lower part of the GaAs layer is unchanged. The results clearly suggest that the GaAs layer can play a role as a diffusion path for exchanging the arsenic and oxygen. Since the oxidation of AlAs is far more reactive than that of GaAs, the oxygen bonded to GaAs in a thin cap layer can be easily reduced to the under-layer of AlAs without a severe modification of GaAs lattice structure.