Porous silicon Bragg flakes towards optical sensing

Details

Supervisors

Francis, Laurent

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil physicien, à finalité spécialisée

Abstract

enPorous silicon (PSi) is a composite material that is known for its simplicity and versatility. There are numerous applications, including optical sensing. An optical sensor using a porous silicon part can be improved with the presence of a Bragg stack at the surface, made in the same material. In this work a production process including electroetching is used to create a free-standing PSi membrane, or flake. The optical properties are enhanced by the presence of a Bragg stack on one side. The process is compatible with microfabrication techniques used for semiconductors. The validity and reproducibility of the production process are evaluated in this work. A numerical model is used to better analyse the optical properties of the flake. Different reflecting samples were made and characterized. Their optical properties are measured and compared to the model. Some improvements on the methodology used to characterize the optical properties of the samples were proposed, with a significant noise reduction with these samples. The application in a sensing device is also discussed. Although the sensing response is not yet accurate, the results provide valuable insight into the limitations of the current procedure and suggest possible improvements for future research. While there is still room for improvement in the production and characterization processes, these samples may be used effectively in the future, for chemical or biosensing applications.