Ultrathin nano-sized Al2O3 strips on the surface of por-Si

Abstract

The objective of this paper is to obtain nano-sized Al2O3 strips on the surface of nanoporous silicon surface as well as fundamental investigations of structural, optical and morphological properties of the materials.While analysing the results, we were able to prove for the first time that the use of ion plasma sputtering allows one to obtain ultrathin nanostructured Al2O3 films as unidirectional fibres arranged by 300–500nm away from one another on a porous silicon layer. Such mechanism of the growth of aluminium oxide strips is stipulated by the morphology of porous silicon layer obtained as a result of etching of the virgin silicon plate; that in turn determines distinctions in the morphology of ultra-thin Al2O3 film.The results of optical spectroscopy shows that the Al2O3 nano-sized strips of the heterophase structure of Al2O3/por-Si/Si(111) is good at transmitting electromagnetic radiation of 190–900nm. It is shown that the intensity of photoluminescence excited by the heterophase structure Al2O3/por-Si/Si(111) is by 30% higher than that excited by the film of the porous layer.The analysis of dispersion of refractive index in the investigated systems showed that its values for the heterophase structure Al2O3/por-Si/Si(111) in the entire range of the wavelengths of the deflection is considerably higher than that those ones of Al2O3 grown under similar conditions using single-crystalline silicon Si(111). In the wavelengths of 250–500nm the refractive index of the heterophase structure Al2O3/por-Si/Si(111) is similar to that one of por-Si used for growing of the heterophase structure.The observed maximum in the dispersion of the refractive index of Al2O3 nano-sized strips grown on por-Si is identical to the optical absorption edge of the aluminium oxide and is in the range of ~5.60eV. This is consistent with the results of calculations of the optical absorption spectrum for the heterophase structure Al2O3/por-Si/Si(111).The nano-sized structured strips of Al2O3 films on the surface of the heterophase structure can serve as optical transmission channels and are quite efficiently introduced into the standard practices, which is of significant importance for micro- and optoelectronics.