<p> Light emitting silicon nanostructures are of significant interest for photonics due to their potential to act as the source material for a monolithically integrated Si-based light source. This thesis reports on the experimental characterization of such luminescent structures formed in silicon nitride, oxynitride, and rare earth doped silicon oxide thin films. Changes in the electronic structure of the materials have been analyzed using soft X-ray spectroscopy by probing the constituent elements at their absorption edges. The observed near edge structure at these edges is related to the local atomic bonding environment of the probed atoms. Specifically, changes in the near edge structure at the Si K and L3,2 absorption edges can be related to the coordination of silicon atoms within the films.</p> <p> In the silicon nitrides the Si-clustering process has been observed to onset at different anneal temperatures, dependant on film composition. In films that have a small amount of excess Si higher anneal temperatures are required before a significant Si-Si bonding signal is observed. In samples with high concentrations of excess Si this clustering process is observed to occur at temperatures as low as 700 °C. In silicon oxynitride samples only a small fraction of the excess Si forms into clusters within the films. Rather, in these samples the formation of distinct silicon oxide and silicon nitride phases is observed, with strong absorption related to the formation of the oxide phase being observed after annealing at high temperatures (T ≥ 1000 °C). The nanoclusters were determined to be amorphous in nature, rather than nanocrystalline, through the use of high-resolution, energy filtered, and scanning transmission electron microscopy. This behavior was seen even for samples with high excess Si concentrations and annealed at high temperatures. This contrasts with the behavior of silicon-rich silicon oxide thin films were nanocrystals are clearly observed after similar treatments, indicative of the influence of the nitride host matrix on the cluster formation process.</p> <p> Changes in the electronic structure at these edges have been correlated with changes in the bonding structure within the films, as analyzed through Fourier transform infrared spectroscopy, and with the photoluminescent behavior of the films.</p> <p> X-ray excited optical luminescence (XEOL) has been used for the study of rare earth doped silicon oxides, allowing for site specific excitation of the films in order to analyze the origin of luminescence in the films. In O-rich samples the luminescence of the films has been observed to be strongly excited at O-related absorption edges while in Si-rich samples XEOL is observed at Si-Si bonding absorption energies. The results indicate the presence of different sensitization pathways towards luminescence in the films, including the formation of oxide or silicate phases.</p> / Thesis / Doctor of Philosophy (PhD)

<p>Please email me at kdunn@celccocontrols.com to confirm receipt of my thesis.</p> <p>Thanks,</p> <p>Kayne</p> / <p>In current microelectronic interconnect technology, significant delay is incurred due to capacitances in the intermediate and global interconnect layers. To avoid capacitive effects optical interconnects can be used; however conventional technologies are expensive to manufacture. One method to address these issues is to make use of quantum confinement effects and states lying within the bandgap of the material to enhance luminescence in a CMOS compatible silicon based system. Thin SiCxNy films appear to be suitable to work as luminescent silicon based films due to their lower direct bandgap and chemical stability but have not yet been studied in great detail.</p> <p>This thesis is an exploratory work aiming to assess the suitability of SiCxNy films for the above applications and to identify future research areas. The films analyzed in this thesis were manufactured on the inductively coupled plasma-chemical vapour deposition reactor (ICP-CVD) at McMaster University. The ICP-CVD produces films of high uniformity by using a remote RF plasma and an arrangement of high vacuum pumps to attain a vacuum on the order of 10-7Torr.</p> <p>Several experimental techniques have been used to analyse the films. The complex index of refraction has been determined through the use of ellipsometry giving results typical of that of a-SiNx:H. The photoluminescence spectroscopy results show a large broad emission peak with at least one shoulder at higher energies. The precise luminescence mechanism(s) could not be identified though a strong relationship with the bonding state of nitrogen has been found. The composition and structure of the films, as determined through ion beam measurements, infrared absorption measurements, and transmission electron microscopy measurements demonstrate the formation of a two phase structure consisting of carbon rich clusters surrounded by a mostly silicon nitride matrix. These carbon rich regions have some graphitic character and act to dampen the luminescence.</p> / Master of Applied Science (MASc)