Periodic Reporting for period 1 - POTION (Photodiode integration on silicon nitride)
Période du rapport: 2021-03-01 au 2023-02-28
In this project the fellow, Gabriele Navickaite, conceived and realized monolithic integration of semiconductor photodetectors on top of a passive Silicon Nitride (SiN) Photonic Integrated Circuit (PIC).
This project showed, for the first time, the monolithic combination of the SiN passive platform with an active semiconductive element and thus constitutes an important learning towards further integration.
POTION helped to show that monolithic photodiode integration with SiN still has a lot of challenges, due to the requirements related to different temperature budgets to keep a low-loss SiN and to form ideal single-crystalline silicon or germanium layers for high-performance photodiodes. The project evidenced that other heterogeneous integration techniques for the integration of optimized SiN passives with state-of-the-art active devices would be desirable. Nevertheless, the execution of POTION was crucial to obtain the first results, which will help to make more educated decisions in future technology developments of active integration.
This project showed, for the first time, the monolithic combination of the SiN passive platform with an active semiconductive element and thus constitutes an important learning towards further integration.
POTION helped to show that monolithic photodiode integration with SiN still has a lot of challenges, due to the requirements related to different temperature budgets to keep a low-loss SiN and to form ideal single-crystalline silicon or germanium layers for high-performance photodiodes. The project evidenced that other heterogeneous integration techniques for the integration of optimized SiN passives with state-of-the-art active devices would be desirable. Nevertheless, the execution of POTION was crucial to obtain the first results, which will help to make more educated decisions in future technology developments of active integration.
Understanding the properties of different materials is essential for designing and manufacturing high-quality products, and during this project reliable methods for characterizing the physical and chemical properties of different materials were developed.
Integrated photodetectors were realized on top of a standard SiN wafer with 800 nm-thick SiN photonic waveguide layer, which were optimized for operation in the optical C-band. Two fabrication runs were completed, including SiN and photodetectors on the same wafer, with two process integration strategies. The fabrication process involved several critical steps such as lithography, deposition, etching, and cleaning. Each step required careful optimization and attention to detail to ensure the desired outcome was achieved.
A proof-of-concept detector working in the infrared wavelength range was demonstrated. A parametrized design of integrated photodiode test waveguides was included to enable the extraction of optical losses, responsivity, and quantum efficiency. Design and simulation of the integrated photodiode as well as the material and process developments were the main focus during the execution of this project. Integrated photodiodes were characterized using electro-optical set up as well as electrical probe stations.
During this project, the fellow was exposed to different areas of photonics integration development. The work involved deep training in optical design concepts and cases of use, as well as in opto-electrical characterization. The main focus of POTION was however, to deepen the fellow’s skills in microfabrication (Class 100 cleanroom - CMi, EPFL) as well as being exposed to 200 mm wafer processes within the framework of LIGENTEC’s established partnership with an the worldwide recognized CMOS foundry, XFAB, in France. This experience was very valuable not only for technical skills development but also for career development.
Integrated photodetectors were realized on top of a standard SiN wafer with 800 nm-thick SiN photonic waveguide layer, which were optimized for operation in the optical C-band. Two fabrication runs were completed, including SiN and photodetectors on the same wafer, with two process integration strategies. The fabrication process involved several critical steps such as lithography, deposition, etching, and cleaning. Each step required careful optimization and attention to detail to ensure the desired outcome was achieved.
A proof-of-concept detector working in the infrared wavelength range was demonstrated. A parametrized design of integrated photodiode test waveguides was included to enable the extraction of optical losses, responsivity, and quantum efficiency. Design and simulation of the integrated photodiode as well as the material and process developments were the main focus during the execution of this project. Integrated photodiodes were characterized using electro-optical set up as well as electrical probe stations.
During this project, the fellow was exposed to different areas of photonics integration development. The work involved deep training in optical design concepts and cases of use, as well as in opto-electrical characterization. The main focus of POTION was however, to deepen the fellow’s skills in microfabrication (Class 100 cleanroom - CMi, EPFL) as well as being exposed to 200 mm wafer processes within the framework of LIGENTEC’s established partnership with an the worldwide recognized CMOS foundry, XFAB, in France. This experience was very valuable not only for technical skills development but also for career development.
Within POTION, an integrated process flow to monolithically form photodiodes evanescently coupled to SiN waveguide was developed. The approach demonstrates the ability to detect light in the C-band.
This project showed, for the first time, the monolithic combination of the SiN passive platform with an active semiconductive element and thus constitutes an important step towards further integration. It clearly fills a market gap in the growing integrated photonics business.
Despite this, the project also showed the drawbacks of monolithic integration, and helped to understand the need to pursue a path towards heterogeneous integration. This wasn’t the original goal of POTION, nevertheless this also led to very important business and research opportunities in the company and for the fellow, with successful project applications in the field of heterogeneous integration.
This project showed, for the first time, the monolithic combination of the SiN passive platform with an active semiconductive element and thus constitutes an important step towards further integration. It clearly fills a market gap in the growing integrated photonics business.
Despite this, the project also showed the drawbacks of monolithic integration, and helped to understand the need to pursue a path towards heterogeneous integration. This wasn’t the original goal of POTION, nevertheless this also led to very important business and research opportunities in the company and for the fellow, with successful project applications in the field of heterogeneous integration.