We have carried out a transmission electron microscopy based study of AlGaAs–Al(oxide) heterolayers created by lateral sidewall wet oxidation and identify the oxide phase formed as a consequence of the oxidation of AlAs to be γ-Al2O3, with the cubic Fd 3m structure. The oxide-semiconductor interface is weak and porous, possibly due to the high stress loads developed during oxidation, and we propose that the fast oxidation rates are a consequence of reactants transported to the oxidation front along the porous interface.

We report a study of the desorption behavior of Ga on the GaN(0001) surface and the growth behavior of GaN during molecular beam epitaxy. A desorption activation energy of 2.2±0.2 eV is measured for Ga adatoms. Porous columnar features in the GaN microstructure are observed that are enhanced by higher growth temperatures and eliminated by growing Mg or Si doped GaN. We propose a model for this observation.

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Selective pair luminescence has been used to measure the exicted states of the shallow acceptors C, Zn, Si, and Ge in GaAs. Data for Ge are presented here for the first time while the sets of excited state energies of C, Zn, and Si are completed. These results show that the energies of the p-symmetric impurity states are influenced by the impurity potentials. The germanium excited states are found to be shifted by 3 meV with respect to the valence band compared to the corresponding states in C, Zn, and Si.