Porosity and roughness determination of porous silicon thin films by genetic algorithms

The problem of determining the porous silicon (PSi) optical constants, thickness, porosity, and surface quality using just reflectance data is board employing evolutionary algorithms. The reflectance measurements were carried out of PSi films over crystalline silicon (c-Si) substrate, and the fittin...

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Bibliographic Details
Published inOptik (Stuttgart) Vol. 173; pp. 271 - 278
Main Authors Ramirez-Gutierrez, C.F., Castaño-Yepes, J.D., Rodriguez-Garcia, M.E.
Format Journal Article
LanguageEnglish
Published Elsevier GmbH 01.11.2018
Subjects
Effective medium approximation
Optical admittance
Optimization
Reflectance
Refractive index
Optical admittance
Effective medium approximation
Refractive index
Optimization
Reflectance
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Summary:The problem of determining the porous silicon (PSi) optical constants, thickness, porosity, and surface quality using just reflectance data is board employing evolutionary algorithms. The reflectance measurements were carried out of PSi films over crystalline silicon (c-Si) substrate, and the fitting procedure was done by using a genetic algorithm (GA). The PSi is treated as a mixture of c-Si and air. Therefore, its effective optical constants can be correlated with the porosity through effective medium approximation (EMA). The results show that genetic fitting has a good match with the experimental measurements (near UV–vis reflectance) and the thickness obtained by scanning electron microscopy (SEM).
ISSN:0030-4026
1618-1336
DOI:10.1016/j.ijleo.2018.08.019