Khatsevych I. Physical properties of light-emitting structures with silicon nanoclusters got a method ion-stimulated synthesis

The thesis is devoted to the investigation of physical properties of light-emitting structures with silicon nanoclusters in dielectric matrix synthesized by different methods and influence of an ion-beam and thermal modification on properties of such structures. Light-emitting properties of structures with Si-nc embedded in the matrix of SiO2, synthesized by the methods of plasma enhanced chemical vapor deposition, thermal evaporation and ion implantation, was investigated. It was shown that photoluminescence of structures with Si-nc depend on the method of synthesis of SiOX films. The influence of impurities of aluminium and titanium on light-emitting properties of structures with Si-nc was studied. It was determined that introduction of aluminium enhanced the intensity of photoluminescence of such structures due to the increase of concentration of silicon excess and passivation of the dangling bonds. The physical model of influence of nitrogen on formation and radiative recombination in structures from Si-nc was proposed. According this model nitrogen stabilized of the sizes and concentration of silicon nanoclusters and modified of the interfaces between nanoclusters/matrix at the expense of passivation of the centers nonradiative recombination and creation of the additional canters radiative recombination. New method of ultrasound-assisted ion-beam synthesis for formation of structures with Si-nc in the matrix of SiO2 was applied. It was shown that ultrasound treatment reduces concentration of the suboxide states on the interfaces between silicon cluster and silicon dioxide matrix. It was observed that photoluminescence properties are strongly correlated with the concentration of the suboxide states thereby providing an evidence that besides a quantum confinement effect the chemical composition of the interface between nc-Si and matrix SiO2 is important. The increase intensity of photoluminescence structures with Si-nc after low-temperature annealing at 450 С in a mixture of nitrogen and oxygen was investigated and explained. The physical mechanism of this effect consist in reconstruction of the Si-nc/matrix interfaces and formation at these interfaces of the energy levels, which take part in recombination of the non-equilibrium charge carriers.