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In the frame of this work microporous silicon (mPSi) is filled with magnetic metals (Ni, Co) resulting in a composite system with specific magnetic properties corresponding to its branched morphology. The results are compared with mesoporous silicon (PSi) loaded with Ni nanoparticles (NPs) of comparable size. The two systems offer drastic differences in their magnetic response. Furthermore mPSi offers luminescence in the visible range, whereat this behavior is due to the small structure size in the range of a few nanometers (2 – 5 nm). The morphology of mesoporous silicon shows straight pores with a diameter up to 50 nm. Due to the different template morphology the responding magnetic behavior shows distinct properties related to the two systems, although the size of the metal deposits is in a similar size range. The Ni loaded mPSi system merges optical and magnetic properties leading to a nanocomposite appropriate for possible magneto-optical devices.

Bi-metal magnetic nanostructures have been deposited within porous silicon (PSi) to influence the magnetic switching behavior of the PSi/metal nanocomposite and further to enhance the energy product of the system compared to single metal nanocomposites. These nanocomposites consisting of two ferromagnetic metals have been achieved by two different routes. On the one hand both metals have been deposited alternatingly out of one solution and on the other hand the two metals have been deposited by using different metal salt solutions alternately. The latter system shows two distinct slopes of the hysteresis due to the different saturation behavior of the two types of deposited metal, whereas the system produced from one electrolyte shows no kink which indicates exchange coupling between the two metals. The comparison of these two types of samples shows that the one offering exchange coupling exhibits nearly a doubled coercivity and remanence.

Metal deposition within porous silicon is under investigation for more than 2 decades whereat the incorporation of metals has been examined with respect to the influence of the light emission or to the modification of the conductivity of porous silicon but also to the growth of different metals inside macropores has been studied in detail. In the frame of this work the deposition of different metals, especially ferromagnetic ones within high aspect ratio mesopores will be elucidated with respect to the specific nucleation and growth of the deposited nanostructures under various conditions. To ensure that the nanostructure growth starts at the pore bottom pulsed electrodeposition has been used. Since mesoporous morphologies offer dendritic pore walls these structural inhomogeneities of the matrices are critical for the deposition process. From experiments one can see that the nucleation preferentially starts at the “tops” of the rough surface. The electrochemical parameters offer the opportunity, but have to be chosen exactly, to obtain desired results. A further key point of the presentation is the magnetic characterization of the various nanocomposites. Magnetic characterization of the three dimensional nanowire/nanoparticle arrays shows that not only the morphology of the deposited metal structures (size, shape, distribution) determines the magnetic properties but also the morphology of the template, e.g. side-pores of different length. In this sense magnetic coupling between the nanostructures plays a crucial role and is strongly influenced by morphological parameters. From all these findings it is possible to prepare samples with specific magnetic properties which could be of interest for on-the-chip devices.

In the frame of this work porous silicon templates with different morphologies, especially with respect to the roughness of the pore-walls are filled with diverse ferromagnetic metals to fabricate self-assembled three dimensional arrays of nanostructures (wires, particles) with distinct magnetic properties. The fabricated templates offer a quasi-regular self-assembled pore-arrangement with oriented pores. Also the pore-filling is self-assembled by electrochemical deposition and there are multiple possibilities to tailor the magnetic behavior of these systems such as material, morphology, inter particle distance or interfaces. One critical parameter for this purpose is the roughness of the pore walls and the surface of the metal structures, respectively. To vary the morphology of the templates also magnetic field assisted etching has been employed and a remarkable decrease of the dendritic pore growth has been achieved resulting in smoother pore walls. Within the pores of these templates ferromagnetic metals are deposited and the modification of the magnetic properties compared to metal structures embedded in conventional etched (without magnetic field) porous silicon templates has been figured out. The magnetic anisotropy between easy axis and hard axis magnetization could be increased significantly and furthermore the magnetic behavior becomes comparatively hard magnetic. These properties can be ascribed to less magnetic coupling between nanostructures of adjacent pores and modified stray fields due to less dendritic metal nanowires. The magnetic behavior of three dimensional metal nanowire/nanoparticle arrays with regard to morphological parameters as well as to the influence of the inner interfaces of the composites will be presented. The presented system is of interest due to the silicon base material and the broad tunability of the magnetic properties for integrated magnetic and magnetooptic devices.

Due to the fact that both materials porous silicon as well as iron oxide nanoparticles are biocompatible and porous silicon can be functionalized easily to attach therapeutic nucleotides the aim is to create a cytocompatible arrangement to promote magnetically guided delivery into targeted cells. Furthermore porous silicon dissolves in body fluid dependent on the porosity which increases the possible applications. Within the frame of this work the field and temperature dependent magnetic properties of the nanocomposite have been investigated as well as its cytocompatibility according to the porous silicon morphology and the iron oxide particle size.

Porous silicon in the mesoporous regime is used as template for electrodeposition of ferromagnetic metals within the pores to fabricate self-assembled three dimensional arrays of nanotubes, nanowires or nanoparticles. Depending on the electrochemical deposition parameters the geometry of the metal deposits can be tuned and thus desired magnetic properties can be achieved. The morphology of the templates is modified due to different anodization processes. Additional to a conventional etching process magnetic field assisted etching is applied. Furthermore the magnetic properties in dependence on the morphological characteristics, especially the pore-growth of the porous silicon are investigated. An important point is the concomitant modification of the magnetic coupling of metal nanostructures of adjacent pores.