Photoluminescence Enhancement Of Silicon-based Semiconductor Materials By Coupling With Metal Surface Plasmon

With the rapid development of large scale integrated electronic circuit based on the silicon materials, signal delay induced by over-high interconnect and over-heat of device is becoming serious problems. It poses a dramatic difficulty to the continuous development of the microelectronic industry represented by integrated electronic circuit. Optoelctronic system is a potential solution to this problem, but silicon makes a poor material for light emitter due to its indirect band structure which limits the application in optoelctronics. So obtaining high-efficiency silicon-based light emitting mateials and devices is very important. Suface Plasmon at the metal interface can increase the rediative decay rates of the light emitter thanks to the high localized electromagnetic field at resonance. Moreove, by matching the wavevector of surface plasmon and light radiation using scattering, the energy lost at the metal electrode can be recovered which will improve the efficiency of the light emitting devices. Then using suface plasmon to increase the light emission has become a hot topic in recent years. Evidentsly, using surface plasmon to enhance the light emission is expected to find wide potential applications in silicon-based light emitters.In this dissertation, metal island films and core-shell structure were produced and the factors that affect its morphology and suface palsmon resonance properties were investigated. Then the light emission of ZnO and silicon rich silicon nitride films was enhanced by coupling with Ag island films. The coupling mechanism and the factors affecting the coupling were analyzed. The primary significant results were summarized as follows:(1) Ag island films were prepared by sputtering, and the morphology and surface plasmon were found dependent on the sputtering time and temperature. Thermal processing changed the morphology of Ag island films and then tuned the surface plasmon resonance wavelength. Large blueshift can be obtained by rapid thermal processing at 200℃, and conventional thermal processing at different temperature can tune the resonance wavelength continuously.(2) Ag and Au core-shell arrays were prepared by sputtering using PS sphere as templates. The core-shell morphology and surface palsmon resonance were changed by sputtering time. With the increases of sputtering time, the shell thickness increased and the dipole surface Plasmon blueshifed. The PS template can be removed by thermal processing. The dielectric environment was changed by PS removal which led to the blueshift of the dipole resonance.(3) The band gap emission of ZnO films was enhanced and the defect emission was quenched by coupling with the surface Plasmon of Ag island films. It was found that the band emission and defect emission were coupled with out-of-plane and in-plane surface plasmon resonance mode of Ag island films respectively. The absorption of the in-plane surface plasmon mode induced the quenching of the defect emission and it can be recovered by tuning the in-plane resonance mode using thermal processing. The influence of Ag island size, detection directions, the thickness of ZnO films and the temperature on the surface plasmon coupled emission enhancement was investigated, and the coupling mechanisms under different conditions were elucidated.(4) The Ag island films coupled emission enhancement of ZnO films was found dependent on the substrate. Theoretical computation results shows that when using high refractive index substrate, the substrate mode has a competition with the surface palsmon mode in energy, which then affect the energy of surface plasmon radiative scattering, leading to the emission quenching. The four-layer structure which avoided the energy lost to substrate mode was designed to enhance the emission of silicon based ZnO film.(5) The photoluminescence of silicon rich silicon nitride films was enhanced by coupling with surface plasmon of the Ag island films and the coupling mechanism of the excitation and radiative process was investigated. The results show that the surface plasmon enhanced emission was more decided by excitation efficiency enhancement than radiative scattering enhancement. It was found that the photoluminescne enhancement was not only dependent on the Ag island size, but also on the relative spectral position between the emitting wavelength and the surface plasmon resonance band, and the latter also influenced the emission band position of the silicon rich silicon nitride.