Increasing the photoluminescence intensity of silicon nitride by forming K and N radioactive centres

Creating a light emitter to transfer an electrical signal by optical way has a great importance in development of optoelectronics. The silicon nitride films studied by photoluminescence techniques, and determined luminescence is associated with presence of an extended zone of tail states. Defects play the main role in radiative recombination for structures annealed at 600 °C and 1100 °C. Photoluminescence (Pl) intensity of obtained films by plasma enhanced chemical vapor deposition is increased after annealing at 600 °C which are related to increased concentration of defects as a result of broken Si–H and N–H bonds. Due to the formation of N-centers through the breaking of N–H bonds, annealing at 1100 °C led to sharp decrease in the luminescence intensity 5 and 3 times for SiN1.1 and SiN1.5 samples respectively. Replacement of Si-Si bonds by Si-N enhance Eg with increasing stoichiometric parameter, which leads to blue shift edge of photoluminescence maximum. Carbon implantation of silicon nitride films with extra Si obtained by Plasma Enhanced Chemical Vapor deposition at 1x1014 cm‒2, 2x1015 cm‒2, and 1x1016 cm‒2 fluencies, in combination with prolonged annealing at 1100 °C temperature leads to the formation of additional K-centers.

Low-energy Ar+ and N+ ion beam induced chemical vapor deposition using hexamethyldisilazane for the formation of nitrogen containing SiC and carbon containing SiN films

We proposed an experimental methodology for producing films on substrates with an ion beam induced chemical vapor deposition (IBICVD) method using hexamethyldisilazane (HMDS) as a source material. In this study, both HMDS and ion beam were simultaneously injected onto a Si substrate. We selected Ar+ and N+ as the ion beam. The energy of the ion beam was 101 eV. Temperature of the Si substrate was set at 540 °C. After the experiments, films were found to be deposited on the substrates. The films were then analyzed by Fourier transform infrared (FTIR) spectroscopy, stylus profilometer, X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy (XPS). The FTIR and XPS results showed that silicon carbide films containing small amount of nitrogen were formed when Ar+ ions were injected in conjunction with HMDS. On the other hand, in the cases of N+ ion beam irradiation, silicon nitride films involving small amount of carbon were formed. It was noted that no film deposition was observed when HMDS alone was supplied to the substrates without any ion beam injections.

Measurement of the properties of MetalMUMPS® thin films

The metal multi-user micro-electro-mechanical-systems (MEMS) processes (MetalMUMPs®) micro-machining process includes two silicon nitride films, one polysilicon film, and one nickel film for constructing various MEMS devices. This thesis presents property measurements of the metalMUMPs® silicon nitride and nickel films. Fabricated MetalMUMPs® silicon nutride prototypes were used to experimentally determine a Young’s modulus of 209 GPa and a residual stress difference of 169 MPa for the silicon nitride films. A method, which uses the deformations along the width of bi-layered cantilever beams, was proposed to determine the residual stress difference of the two silicon nitride films. Fabricated MetalMUMPs® nickel prototypes were used to experimentally extract a Young’s modulus of 159 GPa and a residual stress gradient of -4.72 MPa/m for the nickel film. A micro bridge mechanism was developed to lift long silicon nitride beams for the determination of the residual stress difference of the two silicon nitride films.

Measurement of the properties of MetalMUMPS® thin films

The metal multi-user micro-electro-mechanical-systems (MEMS) processes (MetalMUMPs®) micro-machining process includes two silicon nitride films, one polysilicon film, and one nickel film for constructing various MEMS devices. This thesis presents property measurements of the metalMUMPs® silicon nitride and nickel films. Fabricated MetalMUMPs® silicon nutride prototypes were used to experimentally determine a Young’s modulus of 209 GPa and a residual stress difference of 169 MPa for the silicon nitride films. A method, which uses the deformations along the width of bi-layered cantilever beams, was proposed to determine the residual stress difference of the two silicon nitride films. Fabricated MetalMUMPs® nickel prototypes were used to experimentally extract a Young’s modulus of 159 GPa and a residual stress gradient of -4.72 MPa/m for the nickel film. A micro bridge mechanism was developed to lift long silicon nitride beams for the determination of the residual stress difference of the two silicon nitride films.

Effect of Thermal Annealing on the Photoluminescence of Dense Si Nanodots Embedded in Amorphous Silicon Nitride Films

Luminescent amorphous silicon nitride-containing dense Si nanodots were prepared by using very-high-frequency plasma-enhanced chemical vapor deposition at 250 °C. The influence of thermal annealing on photoluminescence (PL) was studied. Compared with the pristine film, thermal annealing at 1000 °C gave rise to a significant enhancement by more than twofold in terms of PL intensity. The PL featured a nanosecond recombination dynamic. The PL peak position was independent of the excitation wavelength and measured temperatures. By combining the Raman spectra and infrared absorption spectra analyses, the enhanced PL was suggested to be from the increased density of radiative centers related to the Si dangling bonds (K0) and N4+ or N20 as a result of bonding configuration reconstruction.

Low-Temperature and Low-Pressure Silicon Nitride Deposition by ECR-PECVD for Optical Waveguides

We report on low-temperature and low-pressure deposition conditions of 140 °C and 1.5 mTorr, respectively, to achieve high-optical quality silicon nitride thin films. We deposit the silicon nitride films using an electron cyclotron resonance plasma-enhanced chemical vapour deposition (ECR-PECVD) chamber with Ar-diluted SiH4, and N2 gas. Variable-angle spectroscopic ellipsometry was used to determine the thickness and refractive index of the silicon nitride films, which ranged from 300 to 650 nm and 1.8 to 2.1 at 638 nm, respectively. We used Rutherford backscattering spectrometry to determine the chemical composition of the films, including oxygen contamination, and elastic recoil detection to characterize the removal of hydrogen after annealing. The as-deposited films are found to have variable relative silicon and nitrogen compositions with significant oxygen content and hydrogen incorporation of 10–20 and 17–21%, respectively. Atomic force microscopy measurements show a decrease in root mean square roughness after annealing for a variety of films. Prism coupling measurements show losses as low as 1.3, 0.3 and 1.5 ± 0.1 dB/cm at 638, 980 and 1550 nm, respectively, without the need for post-process annealing. Based on this study, we find that the as-deposited ECR-PECVD SiOxNy:Hz films have a suitable thickness, refractive index and optical loss for their use in visible and near-infrared integrated photonic devices.