Development and characterization of structures and materials applied in photovoltaics, and in photonics

Abstract

The objective of this work was primarily to study the effective medium and materials through various characterization techniques(optical,structural,electronic) applied in the photovoltaic(PV)and the biophotonic (BP)domain.The optical and electronic properties of monocrystalline Si(100)with ananostructured surface“Black Silicon”,obtained by an inductively coupled plasma(ICP)dry reactive ion etching(RIE)process in a gas mixture of SF6 and O2(coated and not coated samples),were characterized using SEM,CLSM,XRD,EDX,SE,UV-Vis, PL,REM,and XPS, especially with regard to photovoltaic applications. Thereafter,a biophotonics part is focused on optical characterization(axial resolution)of fluorescence correlation spectroscopy(FCS)configuration and widefield microscopy imaging of fluorescent molecules in a heterogeneous medium as well(effective medium).A systematic study using two different FCS methods with known(and unknown)concentration(or diffusion coefficient)has been implemented in parallel with the PSF method.So,based on the statical analysis of fluorescence fluctuations of fluorescent molecules,both FCS and PSF methods are in agreement with small uncertainties.Afterward,the optical response of the observed heterogeneous structure is modeled by a combination of the Gibson-Lanni(scalar model)and the effective medium approximations(EMA)such as Lorentz-Lorenz,Maxwell-Garnett, Bruggeman,and Chemical mixture models.The obtained results demonstrate that this model is not only effective to predict and interpret the image obtained by the widefield optical microscope but also to improve the PSF results.