Macropores in Si: fundamental study and prospective applications
This work is to a great extent multidisciplinary. It covers such areas as: simulations and modelling of fundamental electrochemical processes at the Si-HF interface, in particular the oscillatory behaviour of the Si electrode; investigation of the pore growth phenomenology in n-Si; development of novel optical elements based on Photonic Crystals (PCs) as well as concepts for new generation of metamaterials, i.e. Negative Index Materials (NIM). A detailed analysis of the electrochemical current and potential oscillations at the Si–HF interface is presented. Calculations and simulations are based on the current burst model, which was extended to the simulation of various oscillatory phenomena at the Si–HF interface. Apart from a detailed analysis of current oscillations in various modes, potential oscillations could be simulated for the first time, too. Much progress has been made towards a better understanding of the macropore growth phenomenology by using the input from the CBM and results from a newly introduced in-situ characterization technique – Fast Fourier Transformed impedance spectroscopy. For the first time a completely new impedance spectroscopy mode is proposed – (backside) photo impedance. In particular, the pore quality could be quantified for the first time in-situ, especially by extracting the valence of the ongoing process. The study paves the way towards an automatized etching system where the pore etching parameters are adjusted in-situ during the pores etching process. A new type of NIM is proposed and tested. Very good focusing properties of plane plate lenses, based on this material, could be obtained. Another topic addressed in this thesis was PCs with unusual index of refraction, i.e. neff < 1, were investigated, and optical components with a wide range of functionality based on this class of PCs are designed and tested. Envisioned uses included lenses, filters, beam splitters, antennas, etc.