Electrochemically nanostructured materials and its applications in electronics S. Lazarouk Belarusian State University of Informatics and Radioelectronics Minsk, Belarus

Electrochemically nanostructured materials are formed by electrochemical anodization processes Porous silicon and porous oxides of valve metals (Al, Ti, W, Nb) can be fabricated by this approach Laboratory equipment

Equipment for electrochemical anodization on semiconductor wafers in industry production

Photoluminescent properties of porous silicon films Porous silicon samples with photoluminescent peaks in different parts of the visible range Typical photoluminescent spectrum of porous silicon film Electroluminescent spectrum of porous silicon film

Porous silicon Light emitting diodes (LEDs) based on porous silicon Photo of fragment of optical interconnects based on porous silicon LED Structures Applications Schematical view of optical interconnects based on porous silicon LEDs Pore diameters can be varied in the range from subnanometers up to few microns Photo of porous silicon

Fast oxidation processes in porous silicon films Explosion Combustion Fragments of combustion processes Fragments of explosion processes Light emission kinetics at fast porous silicon oxidation processes Applications: ecologically clean pyrotechnics. self-destructed chips, ignition system for airbag in automobiles, alternative fuel in respect with carbon and hydrocarbon fuels.

MEMS based on energy of porous silicon combustion Schematical view of MEMS based on porous silicon Cross-sectional photo of silicon chip with porous silicon for MEMS Porous silicon impregnated by solid state oxidant Porous silicon combustion Direction of silicon chip movement Schematical view of MEMS operation The estimated impulse ranges from 1 to 10 mN·s, which is very promising for a use of porous silicon as an energetic material in MEMS.

Porous alumina Porous alumina with the tradition cell structure (honey comb cell structure) Applications Planar aluminium VLSI interconnects built in porous alumina: a) surface view; b) cross- sectional view. Porous alumina with the tubular cell structure Porous alumina with the tubular structure can be used for vertical alignment of liquid crystal materials in display devices Schematical view of vertical alignment of liquid crystal molecules in porous alumina Structures

Porous oxides of refractory metals (Ti, W) Photographs of porous titanium and tungsten oxides with different structures : а – tubular structure (cross-sectional view ), b – doublewall tubular structure (surface view), c – sponge like structure (cross-sectional view), d – pillar structure (cross-sectional view). Applications: Porous oxides of refractory metals can be used: - for photocatalitic water purification from organic pollutions; - for anodes in electrochromic displays; - for anodes in pfotoelectrolis cells for water splitting to hydrogen and oxygen а bcd Structures

Conclusion Nanostructured oxides of valve metals are promissing materials indeed for photocatalysis, sensor and electrooptical applications Nanostructured porous silicon LEDs open new possibilities for developing silicon based optoelectronics Nanostructured silicon can be considered as an alternative energetic material in respect of carbon based fuels