Silicon Based Photonic Crystal Light Sources a Dissertation Submitted to the Department of Electrical Engineering and the Committee on Graduate Studies of Stanford University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy

Efficient light generation on silicon is desirable for a variety of applications because of its low fabrication cost relative to III/V semiconductors and because it will enable monolithic integration with electronic components on the same Si platform. We studied silicon-rich silicon nitride with emission in the visible and erbium-doped silicon nitride (Er:SiNx) with emission at 1540 nm. Both of these materials are compatible with the mainstream complementary metal-oxide semiconductor (CMOS) processing technology. This thesis discuses our results on using photonic crystal (PC) cavities to enhance luminescence from these materials. Nano-resonators modify the optical density of states (DOS) to enhance the emission in a fundamentally different way than what is accessible through materials engineering. Specifically, photon emission rate can be enhanced at a particular wavelength because the optical DOS is higher at the cavity resonance, which in turn improves efficiency and allows faster modulation rates. We have demonstrated up to 11-fold enhancement at photonic crystal resonance relative to smooth film at 730 nm and over 20-fold enhancement at 1540 nm. Time resolved measurements on erbium-doped sample confirmed significant enhancement of spontaneous emission rate. In addition, we have observed cavity line-width narrowing with increasing pump power in the erbium-doped sample, resulting from decrease in ground-state absorption by erbium ions as more of them are excited. We achieved excitation of up to 31% of Er ions at cryogenic temperature. This is an important step toward realizing a laser or amplifier based on Er:SiNx in the future.