Abstract
Abstract The thesis focuses on study of light emission of silicon nanocrystals (nc-Si) on one-dimeensional distributed feedback (DFB) structures. First of all, we fabricated SiO2/SiOx/SiO2/Si substrate rib waveguides and used variable-stripe-length (VSL) method to calibrate optical gain coefficient of silicon nanocrystals. The measured optical gain and loss coefficients of the waveguide are 70cm-1and 14cm-1, respectively. Next, Finite difference time domain (FDTD) method, Bragg diffraction theory and coupled mode theory were utilized to design the grating period, grating depth and duty cycle. The optimized grating period and duty cycle are 375nm and 0.7~0.8, respectively, according to the simulation results. To fabricate n-Si DFB, silicon-rich oxide deposited by PECVD was first annealed at 1100°C in vaccum to form nanocrystalline silicon on quart substrate. Then ITO and SiO2 were deposited on the device surface and the DFB structures were patterned by electron beam lithography and the following reactive ion etching. From the measurement results, we observed narrowed photoluminescence (PL) and enhanced peak intensity on the nc-Si DFB structures, showing significant stimulated emission of silicon nanocrystals around the resonant wavelength depending on the designed grating period. For the grating period of 375nm, the FWHM of PL was narrowed form 200nm to 60nm and the intensity was amplified by 3.3 times at the resonant wavelength of 578nm.