| The most critical subject to realize the silicon based monolithic optoelectronic integrated circuits is looking for a high efficient silicon based light source. And it may provide a promising solution to improve the internal quantum efficiency and light extraction efficiency with localized surface plasmon (LSP) and patterned structure, respectively. In this thesis, in order to improve the light emission efficiency of silicon-based light-emitting materials, we investigate LSP enhanced light emitting from oxidized amorphous silicon nitride (a-SiNx:O) films and the optical near-field modulation in fabricating patterned structure by laser interference crystallization. Firstly, we investigated the surface morphology and optical properties of silver island films to analyze the LSP resonance modes depending on the size and distance of silver islands. Then the PL from N-rich a-SiNx:O films grown on the silver island film coated and bare silicon substrate was studied, an enhancement factor up to2.2-fold was observed at422nm. Secondly, we simulated the light intensity distribution with phase shift grating mask (PSGM) by two methods, fresnel diffraction integral and finite-difference time-domain (FDTD), respectively. Periodic silicon nanocrystal (nc-Si) arrays were fabricated by laser interference crystallization on hydrogenated amorphous silicon (a-Si:H) films. The main results and innovation points are listed as follows:1. Silver films were evaporated by EBE and thermal annealing to form islands. Extinction spectrums showed two dipole modes, one of which was pinned around375nm and did not shift with the increase of annealing temperature whereas the other red shifted obviously. When the temperature reached500℃for the samples evaporated silver with thickness of20nm and30nm, the distance between islands was too large to support the coupling of LSP dipole modes, which leaded to a blue shift. For the samples evaporated silver with thickness of20nm after annealing at300℃, islands larger than60nm accounted for52.31%. And it decreased to27.16%when the temperature reached up to400℃, which means scattering would be significantly weakened.2. PL measurement was performed after the deposition of a-SiNx:O films with different Si/N ratios. In order to match the LSP resonance wavelength we chose N-rich a-SiNx:O film as the active layer since its PL peak located within the range of blue light. Sample without silver island film showed PL peak at471nm, sample with silver island film showed main peak at437nm and secondary peak at478nm. Light emission was significantly enhanced around422nm and reached an enhancement factor up to2.2. Then we proved that such enhancement was related to the quadruple mode of LSP according to the reflection spectrum where two minimum showed at432nm and465nm respectively. Temperature-dependent PL further confirmed that the luminescence center was related to the Si-O localized states in N-rich a-SiNx:O films.3. Fresnel diffraction integral method and FDTD method were used to simulate the optical near-field modulation by PSGM, and periodic nc-Si arrays were fabricated by laser interference crystallization. The experimental results were consistent with the simulations. With the optical modulation by PSGM, the incident plan wave was modulated to be periodically distributed when irradiated on the a-Si:H films. In the case of2D-PSGM with a periodicity of400nm, the peak electric field showed a Gaussian distribution in single period with a maximum up to4.5fold in the center. |
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