Characterisation of porous silicon composite material by spectroscopic ellipsometry

Influence of experimental parameters on physical properties of porous silicon and oxidized porous silicon layers

“…However, for some applications, the PS multilayers are oxidized to decrease absorption losses in order to obtain oxidized porous silicon (OPS) [12,13]. Many authors report quantitative measurements on porosity, growth rate and roughness notably for the case of PS layers [14][15][16][17].…”

Porous silica composite material for non‐linear optical properties: characterisation by spectroscopic ellipsometry and second harmonic generation

“…After this complete oxidation, the residual porosity is 56 %, as deduced from the refractive index measured by "m-lines" method and by using Bruggeman model [3,4], then confirmed by spectroscopic ellipsometry. In fact the porous silicon was completely transformed to porous silica (SiO 2 ) in order to obtain a transparent porous layer [7], and to obtain a good filling of the porous layer by the DR1 molecules [5]. The DR1 molecules (4-[N-ethyl-N-(2-hydroxyethyl)] amino-4'-nitraozobenzene) were dissolved in various solvents and the best result was obtained when the DR1 molecules were dissolved in THF with 20 g/l concentration [5].…”

“…Then, the solution was introduced into the oxidised porous silicon films with a micro-syringe. Uniform distribution of the filling of the porous silicon films by the organic molecules (DR1), from the surface up to the silicon interface, was demonstrated by micro-Raman analysis [5,6], and a concentration about 4% was found [7]. The poling process was carried out by a static electric field of 1000 Volts, applied between two flat electrodes (?…”

“…A large spectral range was necessary for the complete characterisation of the composite material elaboration which exhibits strong absorption in the UV and visible range. Optical properties (complex refractive indexes) and thickness of the composite structure were extracted from the SE data analysis [7]. Second Harmonic Generation (SHG) experiments were then carried out in reflection to avoid the optical absorption of the heavily doped silicon substrate in the near-IR region.…”

Optical properties of thick ordered mesoporous silica membranes

“…These parameters are used to extract the optical constants, composition, porosity, and thickness of porous materials [13]. Of the many models available, the Bruggemann model which uses Effective Medium Approximation (EMA) is considered ideal for porous materials when the wavelength of the incident light is much greater than the dimensions of the pores [9,14]. Figure 9 and Fig.…”