The preparation of non-oxidized Ge quantum dot (QD) lattices embedded in Al 2 O 3 , Si 3 N 4 , SiC matrices by self-assembled growth was studied. The materials were produced by magnetron sputtering deposition, using different substrate temperatures. The deposition regimes leading to the self-assembled growth type and the formation of three-dimensionally ordered Ge QD lattices in different matrices were investigated and determined. The oxidation of the Ge QDs in different matrices was monitored and the best conditions for the production of non-oxidized Ge QDs were found. The optical properties of the Ge QD lattices in different matrices show a strong dependence on the Ge oxidation and the matrix type.

The application of the grazing-incidence small-angle X-ray scattering (GISAXS) technique for the investigation of three-dimensional lattices of nanostructures is demonstrated. A successful analysis of three-dimensionally ordered nanostructures requires applying a suitable model for the description of the nanostructure ordering. Otherwise, it is possible to get a good agreement between the experimental and the simulated data, but the parameters obtained by fitting may be completely incorrect. In this paper, we theoretically examine systems having different types of nanostructure ordering, and we show how the choice of the correct model for the description of ordering influences the analysis results. Several theoretical models are compared in order to show how to use GISAXS in the investigation of self-assembled arrays of nanoparticles, and also in arrays of nanostructures obtained by ion-beam treatment of thin films or surfaces. All models are supported by experimental data, and the possibilities and limitations of GISAXS for the determination of material structure are discussed.

We investigated the production conditions and optoelectrical properties of thin film material consisting of regularly ordered core/shell Ge/Al and Ge/Si3N4/Al quantum dots (QDs) in an alumina matrix. The materials were produced by self–assembled growth achieved by means of multilayer magnetron sputtering deposition. We demonstrated the successful fabrication of well-ordered 3D lattices of Ge/Al and Ge/Si3N4/Al core/shell quantum dots with a body-centred tetragonal arrangement within the Al2O3 matrix. The addition of shells to the Ge core enables a strong tuning of the optical and electrical properties of the material. An Al shell induces a bandgap shift toward smaller energies, and, in addition, it prevents Ge oxidation. The addition of a thin Si3N4 shell induces huge changes in the material spectral response, i.e., in the number of extracted excitons produced by a single photon. It increases both the absolute value and the width of the spectral response. For the best sample, we achieved an enhancement of over 250% of the produced number of excitons in the measured energy range. The observed changes are, as it seems, the consequence of the large tensile strain in Ge QDs which is induced by the Si3N4 shell addition and which is measured to be about 3% for the most strained QDs. The tensile strain causes activation of the direct bandgap of germanium, which has a very strong effect on the spectral response of the material.

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Recently demonstrated 3D networks of Ge quantum wires in an alumina matrix, produced by a simple magnetron sputtering deposition enables the realization of nanodevices with tailored conductivity and opto-electrical properties. Their growth and ordering mechanisms as well as possibilities in the design of their structure have not been explored yet. Here, we investigate a broad range of deposition conditions leading to the formation of such quantum wire networks. The resulting structures show an extraordinary tenability of the networks’ geometrical properties. These properties are easily controllable by deposition temperature and Ge concentration. The network’s geometry is shown to retain the same basic structure, adjusting its parameters according to Ge concentration in the material. In addition, the networks’ growth and ordering mechanisms are explained. Furthermore, optical measurements demonstrate that the presented networks show strong confinement effects controllable by their geometrical parameters. Interestingly, energy shift is the largest for the longest quantum wires, and quantum wire length is the main parameter for control of confinement. Presented results demonstrate a method to produce unique materials with designable properties by a simple self-assembled growth method and reveal a self-assembling growth mechanism of novel 3D ordered Ge nanostructures with highly designable optical properties.