Plasmon-enhanced silicon nanocrystal luminescence for optoelectronic applications

On the path toward the realization of silicon-based optical emitters for integrated microelectronics, this thesis studies the optoelectronic properties of silicon nanocrystals as a function of their surface passivation and their interactions with plasmonic materials. The first part of the thesis utilizes controlled oxidation exposures and photoluminescence spectroscopy to verify previous theoretical and computational predictions of oxygen-related surface states that effectively narrow the energy band gap of small silicon nanocrystals. The focus of the second half of the thesis is on experimental and computational studies of enhanced luminescence from silicon nanocrystals in the near field of noble metal nanostructures.; Surface plasmon enhancement is a technique that has only recently been applied to semiconductor nanocrystal luminescence. This thesis thoroughly investigates the emission of silicon nanocrystals coupled to gold and silver nanostructures to achieve a new level of understanding of the enhancement effect. By pairing silicon nanocrystals to metal nanostructures, up to ten-fold increases in the luminescence intensity are realized, concomitant with enhancements of the radiative decay rate, the absorbance cross section; and the quantum efficiency. Moreover, coupling at the plasmon resonance frequency is used to tune the nanocrystal emission spectrum. A computational exploration of these experimental observations indicates that the enhancement effects can be ascribed to emission in the concentrated local field that results from the excitation of metal particle plasmon modes. Finally, the process of coupling silicon nanocrystal emitters to plasmonic metals is applied to a silicon-nanocrystal light-emitting diode, and enhanced electroluminescence is realized.