Erbium-doped amorphous silicon nitride light emitters for on-chip photonics applications

Silicon Photonics is considered as a viable, scalable and cost-effective solution to "the interconnect bottleneck" problem. However, the engineering of complementary metal oxide semiconductor (CMOS) compatible light sources is considered the biggest challenge of silicon photonics. Er-doped silicon-based structures are very promising candidates for 1.54 pm operation. Although Er-doped fiber lasers and amplifiers are available for long-haul communications, the small emission cross section of Er severely limits the applicability to small footprint (∼2.5 cm2) optical chip applications due to the small gain x length product. As a result, engineering strategies to boost emission efficiency and optical gain under both optical and electrical pumping in Er-doped CMOS materials need to be developed.;Recently, energy sensitization of Er ions through Si-nanocrystals in Si-rich SiO2 films (Er:SRO) has been demonstrated with excitation cross sections (sigmaexc) of Er ions four-five orders of magnitude larger than sigmaabs. However, this approach suffers from the substantial free carrier losses introduced by Si-nanocrystals and the low fraction of optically active Er ions preventing net optical gain. Hence, novel materials approaches need to be developed.;In this thesis, Er-doped amorphous silicon nitride (Er:SiNx) by N2 reactive sputtering is developed as a CMOS compatible platform for light sources operating under both optical and electrical pumping. The origin of visible PL of SiNx is explained by radiative transitions via localized states at the band-tails of SiNx. The efficient energy transfer between the localized band tails states in SiNx and Er ions is discussed and, sigmaexc is quantified. By performing temperature dependent studies, we demonstrated that the energy transfer is phonon-mediated. Er PL intensity and lifetime are optimized in ErSiN x by varying the fabrication parameters and a fundamental trade-off between Er excitation and emission efficiencies is demonstrated. The origin of non-radiative centers deteriorating Er emission efficiency with excess Si in SiNx films is investigated. Photonic nano-cavities fabricated using active Er:SiNx films are studied, and emission linewidth narrowing due to the onset of stimulated emission along with Er ions transparency threshold are demonstrated under optical pumping paving the way to the engineering of optical amplifiers. Electrical devices were fabricated in Er:SiNx and the carrier conduction mechanism is attributed to Poole-Frenkel emission enabling high current densities in thin films Finally, multi-level Er electroluminescence was observed for the first time at relatively low voltages (<5V). The sigmaexc under electrical pumping was measured to be 6 orders of magnitude larger than sigmaabs.;This thesis work provides systematic structural, optical and electrical studies of Er:SiNx in order to engineer a CMOS compatible light sources for on-chip applications.