Tuning And Applications Of Surface Plasmon In Noble Metal Nanoparticles

Surface plasmon (SP) effect refers to electromagnetic constrained in the vicinity of metal nano structures resulting a strange coupling state of the external free electron with photon. This electron-photon coupling state forms a very strong localized enhancement of electromagnetic field and will change the direction of the propagation of the electromagnetic field in the vicinity of metal nanoparticles. Currently, SP effect of metal nanoparticles have been widely applicated in the field of solar cells and photocatalysis. By experimentally and simulation analysis, this paper is forced on surface plasmon of noble metal nanoparticles with different sizes and morphologies. And explore the SP effect in Si solar cells, and noble metals assisted etching. The main contents are as follows:(1) In order to tune SP, an experimental study was carried out on the fabrication methods, morphology control and arrangement of the metal nanoparticles. By magnetron sputtering annealing, controllable size, shape and distribution of Ag nanoparticles has been achieved. By ultrasonic treatment, Ag nanoparticles with different sizes and morphologies have been obtained. And metal nanoparticles have been ordered by fluid spreading on solid surface.(2) Investigations into the application localized SP of metal nanoparticles in the antireflective layer of conventional silicon-based solar cells. It found that metal nanoparticles combinated with pyramid antireflective structure can significantly reduce the reflectivity of solar cells. By optimizing the size, distribution of Ag nanoparticles, we found that Ag nanoparticles with spherical morphology and diameter about 100 nm have the strongest extinction ability. Effects of temperature on SP of Ag nanoparticle deposited on Si surface has been investigated. By studying the thermal electronic transmission of metal-semiconductor Schottky junction, the relationship between metal Ag nanoparticle and thermal stability of SP has been revealed. The relationship between the thermal stability and the particle size of Ag nanoparticles was revealed by studying the variation of the reflectance of metal-Si composite structures with different temperature. By studying the mechanism of the effect of temperature on the plasmon effect, it is found that the change of the plasmon effect is mainly caused by the temperature effect on electrons in the Schottky junctions of Ag-Si composite structure.(3) Analysis the electron and mass transport mechanism of noble metal assited Si etching process. By preparing different nano-contact manners between nanoparticles and Si substrate, the effect of nano-contact manners on the transmission rate and direction of electrons in etching process has been studied. In common etching liquid ratio conditions, the electron transmission direction by directly through the metal into the solution gradually variable for two directions from the metal wall and the etching into the solution have been found as the contact area between metal nanoparticles and the substrate decreases. By means of loading masks, the transmission direction of reactants in etching process has been investigated. According to the experiment results, Si and Au first form Si/Au alloy on the surface of Au, then enter Au thin film, oxidate on the surface of Au thin film and dissolve into the etching solution. By introducing the SP effect into noble metal assited Si etching process, the effects of SP on the noble metal assited Si etching has been systematically investigated. Greatly acceleration of etching rate and formation of unique craters structure on Si surface has been found around nanoparticles.(4) The model of nanoparticle/pyramid composite anti-reflective structure is build. By the Mie theory and principles of geometric optics, the mechanisms of the enhancement of light trapping by localized surface plasmon have been studied, meanwhile the effect of particle size and size distribution of nanoparticles on localized surface plasmori has been discussed. By building model of the impaction of ultrasonic cavitation on nanowires, the mechanical characteristics of metal nanoparticles with different lengths under sonication have been analyzed. The variation rules of morphologies of metal nanoparticles under sonication have been revealed.