Amorphous And Heterogeneous Silicon Thin Films

Author : Philippe Jean
Publisher :
ISBN 13 :
Total Pages : 145 pages
Book Rating : 4.:/5 (133 download)

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Download or read book Heterogeneous Integration of Amorphous Materials on the Silicon-on-insulator Platform written by Philippe Jean and published by . This book was released on 2022 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon photonics is the platform of choice for the development of low-cost and ultra-compact photonic systems that can be manufactured in high volume and co-integrated with micro-electronics. These advantages contrast with silicon imperfect optical properties, leading the platform to be challenged by emerging materials that promise improved performances for specific tasks. However, emerging platforms struggle to catch up with the rapid advances in silicon photonics fabrication techniques, design methods and components maturity. The heterogeneous integration of emerging materials with silicon provides the best of both worlds: a solution to silicon’s limitations and an accelerated development path for novel materials. The study of heterogeneous integration methods, materials and devices is a rich topic with applications in many technologically important fields. The research conducted in this thesis contributes to the field of heterogeneous integration for the silicon-on-insulator (SOI) platform, with a focus on amorphous materials. Our six contributions touch on various topics from athermal photonics to thin-film science and culminates in a body of work that establishes novel techniques, components, materials and concepts. In our first contribution, we introduce the chalcogenide glass As02S80 as a material for thermal compensation in silicon photonics. In contrast with previous demonstrations, the high-index, low film loss and ability to reflow results in low-loss hybrid waveguides. These results add to the problematically short list of materials for athermal silicon photonics and show the possibility of achieving both high quality factor and thermal stability in a silicon microresonator. In our second contribution, we iterate on the first contribution and demonstrate the use of subwavelength grating waveguides to improve the light-matter interaction in hybrid As02S80-Si waveguides. The added degrees of freedom result in a nearly perfect thermal compensation with a waveguide thermo-optic coefficient reduced to −2.93 × 10−6 RIU/K. Moreover, we show that the soft chalcogenide glass can be reflowed at CMOS compatible temperature to fill the air voids that are systematically formed in the cladding. In our third contribution, we present a novel fabrication technique for etchless chalcogenide waveguides directly coupled to silicon waveguides. The technique is based on micro-trench filling, where oxide opening windows are etched in the silica cladding down to the silicon waveguide layer. An annealing step beyond the glass transition temperature induce dewetting of the thin-film and leads to the formation of smooth rectangular strip waveguides with low propagation loss of 0.7 dB · cm−1.In our fourth contribution, we use the micro-trench filling method to integrate tantalum pentoxide with silicon for the first time. The advantage of using tantala is highlighted through the demonstration of microresonators with excellent thermal stability over a record bandwidth of more than 120 nm. The exceptional linear and nonlinear properties of tantala suggest many more applications for these hybrid microresonators. In our fifth contribution, we propose and demonstrate, through numerical and experimental validation, that the micro-trench filling technique is a universal heterogeneous technique compatible with a very large variety of amorphous materials. Furthermore, we demonstrate high quality factor, ultra-compact chalcogenide microresonators to support the fact that this method does not compromise SOI integration density. This chapter is concluded by a proof-of-concept for a novel multilayer waveguide geometry enabled by the micro-trench filling tech-nique. Finally, in our sixth and last contribution, the dewetting phenomenon is further investigated for the development of self-assembled ultra-low-loss integrated photonics components. We present the results of an in-depth experimental study of the effect of high-temperature annealing on the properties of As02S80 thin-films, showing, among other things, that it is possible to reach atomic-scale surface roughness using this method. This result suggests that dewetting could play a role for future ultra-low-loss photonics since it alleviates the dominant source of loss. This potential is highlighted by demonstrating the highest quality factor (4.7 × 106) in a compact chalcogenide microresonator.