Formation mechanisms and photoluminescence properties of self-organized porous Si/SiO2 structures formed by electrochemical etching of n-type of Si

Abstract

An ordered array of silicon dioxide pyramids were obtained in the course of silicon substrates etching in viscous solution of dimethylformamide. Systematic study was made to establish the influence of etching current and solution composition on the size, density and the shape of SiO2 pyramids. In general, the formation of the structure involves following steps: (i) the porous silicon layer formation at the interface with monocrystalline silicon, (ii) a sol-gel synthesis of the porous SiO2 area on top of the por-Si layer, (iii) formation of cracks in the por-Si layer and (iv) dissolution of the por-Si layer and as consequence the growth of the Si/SiO2 pyramids. The photoluminescence properties of the samples (λex = 405 nm) are determined by morphology of pyramids array.