Peculiarities of the formation and properties of light-emitting structures based on ion-synthesized silicon nanocrystals in SiO _2 and Al _2O _3 matrices

摘要

A comprehensive comparative study of SiO _2 and Al _2O _3 oxide layers with Si nanocrystals formed by Si + ion implantation and high-temperature annealing has been performed. Information on morphology, phase composition, structure, and luminescent properties of ensembles of ion-synthesized silicon nanocrystals has been obtained using confocal Raman microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, electron paramagnetic resonance, and photoluminescence. It has been found that the peculiarities of the formation of nanocrystals, the distribution of nanocrystals over the depth of the implanted layer, the structure, and the character of chemical bonds are similar for both types of oxide matrices; however, the photoluminescence in the wavelength range 600-1000 nm, which is caused by the nanocrystals in the Al _2O _3 matrix, has been observed only in the case of the formation of SiO _2 shells around the Si nanocrystals. The surface oxidation of the Si nanocrystals, which is necessary for the formation of SiO _2 shells, is possible due to the presence of excess oxygen in the Al _2O _3 matrix (the case of Si implantation into the deposited Al _2O _3 film), as well as due to the inflow of oxygen from the annealing atmosphere (the case of Si implantation into sapphire). In order to verify the quantum-confinement mechanism of luminescence, available data on the temperature dependence of the photoluminescence intensity have been analyzed. An analysis of the mechanisms of charge transfer and electroluminescence excitation in diode structures based on thin ion-synthesized layers with silicon nanocrystals has also been performed.