Silicon-on-insulator optoelectronic components for micropower solar energy harvesting and bio-environmental instrumentation

(eng) This work presents an analysis of optoelectronic components fabricated in silicon-on-insulator (SOI) technology. On one hand, the thesis focuses on UV sensors (λ < 400nm) for bio-environmental applications and on the other hand, it studies CMOS integrated photovoltaic cells for micropower solar energy harvesting. The SOI technology features a thin Si film into which lateral PIN photodiodes are optimized. The responsivity is modeled to optimize the spectral response in UV by adequate choices of anti-reflection coatings. Other structures based on silicon-on- nothing and membrane technologies are investigated. A current-to-frequency integrated circuit is designed to interface the UV photodiodes for bio-environmental instrumentation. The circuit consumes a total power of 27μW and is linear with respect to the responsivity of the photodiode. An optical range of 6 decades can be reached if the power consumption is increased. The SOI photosensors are used to quantify the concentration of biological material by UV transmittance. The UV source is implemented by a low wavelength LED which directly illuminates the sample contained either in PCR tubes, or in well microplates or in PDMS channel. The best result is achieved with the complete UV photosensor for which DNA is quantified on a range from 400ng/μL to 40fg/μL, within PCR microtubes. Other measurements performed in PDMS channel are very promising for future co-integration and microsystems. The SOI substrate is also used to integrate novel lateral solar cells, embedded under the buried oxide. Efficiencies of 10% and 15% are reached for ungated diodes for outdoor and indoor irradiances respectively. Gated diodes reach efficiencies of 12% and 22% for the same irradiances and for a maximal frontgate voltage. A lumped-element modeling is also presented for circuit simulator integration. Finally, it is proved that miniaturized SOI solar cells can be designed for supplying various specific integrated circuits with very small die areas.