Growth of Group IV and III-V Semiconductor Materials for Silicon Photonics: Buffer Layer and Light Source Development

High data transmission speeds, high levels of integration, and low manufacturing costs have established Si photonics as a crucial technology for next-generation data interconnects and communications systems. It involves a variety of components including light emitters, photodetectors, amplifiers, waveguides, modulators, and more. Because of its indirect bandgap, silicon is unable to serve as an efficient light source on a chip, hence this has been one of the formidable challenges. Within the framework of the monolithic approach, this thesis presents the study of two essential aspects of this challenge, the optimisation of buffer layers and development of light sources, by incorporating and improving different systems of Group IV thin films and III-V quantum dots (QDs) semiconductor materials. The monolithic approach focuses on the direct epitaxial growth of highly efficient light sources, usually by the epitaxy of III-V semiconductors lasers on a single Si chip. However, because of the material dissimilarities between III-V materials and Si, during the heteroepitaxy, a high density of crystalline defects such as threading dislocations (TDs), thermal cracks and anti-phase domains are introduced, severely impeding the performance and yield of the laser. For instance, TDs act as non-radiative recombination centres, while thermal cracks cause issues with the efficient evanescent coupling of the emitted light with Si waveguide. To address these defects, typically complex buffer growth techniques with micron-scale thickness are employed. The research in this thesis is divided into two parts, namely buffer layer optimisation and light source development. Each part outlines alternative strategies for overcoming the above-mentioned hurdles for monolithic growth. The first part highlights the optimisation of buffer layer growth to reduce threading dislocations for the monolithic integration of high-performance direct-bandgap III-V and group IV light sources on Si. The growth optimisation of low defect-density Ge buffer ...