The epitaxial growth of CeO2 films on SrTiO3(001) has been investigated over a wide range of growth parameters using oxygen-plasma-assisted molecular beam epitaxy. The lattice mismatch for CeO2 on SrTiO3(001) is 2.0% (compressive) if the film nucleates with a 45° rotation about [001] relative to the substrate (i.e., CeO2(001)‖SrTiO3(001) and CeO2[110]‖SrTiO3[100]). Pure-phase, single-crystalline epitaxial films of CeO2(001) with the above epitaxial relationship readily grew on SrTiO3(001) for substrate temperatures ranging from 550 to 700 °C. However, small amounts of (111) and (220) minority orientations also nucleated at the higher substrate temperatures. In addition, the film surface was observed to become progressively smoother with increasing substrate temperature due to more extensive island agglomeration. The highest-quality film surface grown at 700 °C is unreconstructed and oxygen terminated.

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Transmission electron microscopy (TEM) was used to study microstructures formed in GaN irradiated with 600-keV O + ions at room temperature. Three types of defect clusters were identified in the irradiated GaN: (i) basal-plane stacking faults with dimensions ranging from 5 to 30 nm, (ii) pyramidal dislocation loops, and (iii) local regions of highly disordered material. High-resolution TEM imaging clearly revealed that one type of the basal-plane stacking faults corresponded to insertion of one extra Ga-N basal plane in the otherwise perfect GaN lattice. The interpretation of these results indicated that interstitials of both Ga and N preferentially condensed on the basal plane to form a new layer of Ga-N under these irradiation conditions. The formation of these extended defects and their interactions with the point defects produced during irradiation contributed to a dramatic increase in the dynamic recovery of point defects in GaN at room temperature.

Single crystal 6H-SiC has been irradiated 60°off normal with 2 MeV Au 2ϩ ions at 300 K to fluences of 0.029, 0.058, and 0.12 ions/nm 2 , which produced relatively low damage levels. The disorder profiles as a function of ion fluence on both the Si and C sublattices have been determined simultaneously in situ using Rutherford backscattering and nuclear reaction analysis with 0.94 MeV D ϩ ions in channeling geometry along the ͗0001͘, ͗11 02͘, and ͗101 1͘ axes. Along the ͗0001͘ axis at these low doses, similar levels of Si and C disorder are observed, and the damage accumulation is linear with dose. However, along ͗11 02͘ and ͗101 1͘, the disorder accumulation is larger and increases sublinearly with dose. Furthermore, a higher level of C disorder than Si disorder is observed along the ͗11 02͘ and ͗101 1͘ axes, which is consistent with a smaller threshold displacement energy on the C sublattice in SiC. The mean lattice displacement, perpendicular to each corresponding axis, ranges from 0.014 to 0.037 nm for this range of ion fluences. A steady accumulation of small displacements due to lattice stress is observed along the ͗101 1͘ axis, and a detectable reduction of the lattice stress perpendicular to the ͗0001͘ axis occurs at 0.12 Au 2ϩ /nm 2 . There is only a moderate recovery of disorder, produced at and below 0.058 Au 2ϩ /nm 2 , during thermal annealing at 570 K; more significant recovery is observed for 0.12 Au 2ϩ /nm 2 along both the ͗0001͘ and ͗11 02͘ axes.