We have investigated diffusion and activation of boron implanted with 6 keV energy to a maximum concentration of 8.0×1020atoms∕cm3 in crystalline germanium (c-germanium) and preamorphized germanium, employing rapid thermal annealing in the range of 400–600 °C. As-implanted boron profiles in preamorphized germanium are shallower than the ones in c-germanium due to channeling suppression. While boron diffusion is not observed either in c-germanium or during the germanium regrowth from amorphous state, the boron activation level achieved from the two starting phases is significantly different. A boron activation level of 2.4×1020atoms∕cm3 has been found in regrown germanium, while a level of only 1.2×1019atoms∕cm3 is observed in c-germanium. Remarkably, there is no evidence of any residual extended defectivity at the original crystalline/amorphous interface, when preamorphization is performed.

We have studied implant-induced damage, defect annealing, and recrystallization of B, Ga, P, As, and Sb introduced in Ge by ion implantation at high doses, such that dopant chemical concentrations are above the corresponding solubility in Ge, with energies that target about 100-nm junction depths. It is shown that the amount of damage induced in the Ge lattice increases with the mass of the implanted ion, as expected. Implanted B produces local amorphous regions, although crystalline Ge zones are present in the implanted layer. P is a self-amorphizing ion, creating a continuous amorphous layer during implantation. However, a low thermal budget is sufficient to fully regrow the amorphous layer, without evidence of residual extended defects, as evaluated by crosssectional transmission electron microscopy. Conversely, high concentrations of As cause a significant decrease of the regrowth rate of the damaged layer during rapid thermal annealing in the 400-600°C range studied. Finally, high-dose implantation of heavy ions such as Sb induces dramatic morphologic changes in Ge that are not recovered by post-implant rapid thermal annealing.

Time evolution of the chemical profile, electrical activity, and regrowth of P implanted in Ge at a concentration above the maximum equilibrium solubility is investigated at 500°C rapid thermal annealing temperature. During the first anneal, a second, epitaxial regrowth of a part of the amorphous layer leads to P trapping in substitutional sites at a level of about 4×1020atoms∕cm3. However, nonsubstitutional P atoms frozen in the crystal at high concentration during recrystallization form large, inactive precipitates of peculiar circular shape. Simultaneously, long annealing time leads to continuing, extensive P out- and indiffusion affecting both the P chemical profile and junction sheet resistance.

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The appearance of new functionalities and devices arising from size-and shape-dependent properties has triggered the interest in creating well-defined structures at the nanometricscale. While conventional lithography is used to fabricate structures in the range of hundreds of nanometers, self-organizing and self-assembling processes following a bottom-up approach can easily decrease this size limit and also cover cost-effectively much larger surfaces. [1,2] Semiconductors, metals, oxides and molecular materials are different areas where such principles are intensively pursued to generate nanostructures. [1] In particular, self-assembling based on the stress associated to heteroepitaxial growth is an attractive fabrication route in which the generation of semiconductor nanostructures has been extensively investigated [1,3] and, recently, it has spread to other emerging fields such as oxide-based nanotechnology. Complex oxides attract a great interest for a wealth of different physical and chemical properties and applications such as ferromagnetism, ferroelectricity, colossal magnetoresistance, high dielectric constants, catalysis, optical properties, high temperature superconductivity, solar cells, etc.[4] Based on these properties, many device concepts are under investigation requiring lateral confinement at the nanometric scale, [5][6][7] therefore, it constitutes a real scientific challenge to understand the formation mechanisms of nanometric structures. So far the mechanisms that drive self-organized nanodot growth have been studied in certain detail in epitaxial materials prepared from vapor deposition techniques, including oxides [1,[5][6][7] , and either Stranski-Krastanov or Volmer-Weber mechanisms were found to apply. On the other hand, vicinal substrates have been widely considered as templates for growing low dimensional nanostructures. [8,9] The role of lattice steps on the growth mechanism of oxide films has been analyzed by several authors, though the formation of self-organized nanostructures using the terraces as templates has been very scarce. [5,6] Much less attention has been devoted to investigate the capabilities of Chemical Solution Deposition (CSD), [10,11] a preparation methodology bearing a high interest for many functionalities and practical applications requiring the use of large areas or long lengths.[12] Particularly, CeO 2 is a key material which is being extensively investigated because of its very high intrinsic interest in many areas such as catalysis, ionic conductivity, optical and dielectric properties, [13] buffer layer for oxide superconductors, [14,15] or nanotemplates to manipulate the vortex properties in superconducting materials. [16] In the last case, the use of self-organized templates in combination with superconducting films could lead to a wealth of new superconducting phenomena.[17] It appears then as highly demanding, scientifically and technologically, the study of the mechanisms generating nanostructured networks of CeO 2 . Very thin films grown by CSD have b...