Abstract
Surface plasmon polariton (SPP) has attracted considerable attention owing to the property to confine light in sub-wavelength. For instance, the surface plasmon polariton takes place on the metal nanoparticles interface. In this system, due to localizing near tiny metal structure, it has been called localized surface plasmon resonance (LSPR). According to the effect of localized surface plasmon resonance, it can be used to improve absorption in photovoltaic equipment, permitting a considerable reduction in the physical thickness of solar photovoltaic absorber layers. The first purpose of this thesis is to present a new geometry metal nanoparticles structure for increasing scattering by the localized surface plasmon resonance effect. First we analyze basic sphere and cylinder metal nanoparticle in different pitch and at different wavelength. Then we present the new plasmonic structure devices to increase the scattering on metal nanoparticle by adding bullet shape metal nanoparticles. We realize that the relative better rates (bullet nanoparticle and sphere nanoparticle) become stable and relative better rates (bullet nanoparticle and cylinder nanoparticle) decrease when increasing nanoparticle radius. With radio frequency (RF) module solver in COMSOL, the optical structures are simulated and enhancement factor, improving factor, total enhancement factor are extracted. Second, we change the pitch and bullet nanoparticles radius and make that the pitch is six times of the bullet nanoparticles radius. For the smaller pitch, the enhancement factor is better at 700 nm. For the larger pitch, the enhancement factor becomes unstable. The total enhancement factor has an upper value 8.35 % when using the case without bullet nanoparticles as benchmark. Different from some prior works, this thesis is the first to study the change of the enhancement factor between different angles of incident (AOI) at different wavelength. When the wavelength is smaller than 600 nm, the enhancement factor becomes unstable between different AOI. Because the fano effect which is the destructive interference between scattered and unscattered light that occurs below resonance would affect at short wavelength. When the wavelength is larger than 600 nm, the influence of AOI effect becomes small. In addition, the total enhancement factor would be 0.94%, 1.46% and 1.50% and 5.80% which AOI are 0, 30, 45 and 60 degree when using the case without bullet nanoparticles as benchmark. And the enhancement over band gap factor would be 0.49%, 0.91% and 0.89% and 5.51% which AOI are 0, 30, 45 and 60 degree when using the case without bullet nanoparticles as benchmark. In the case that AOI is 45 degree, TE mode offers a distinct advantage over TM mode about 11.82 % when using the case without nanoparticles as benchmark. Therefore, we would just analyze TE mode between different AOI.