This is a very valuable technique for porous materials [16–20] and has already been successfully applied to PSi for the study of cyclic oxidation [21, 22]. Methods PSi layers were prepared by electrochemical etching in the dark of n +-doped (100)-oriented crystalline Si wafers having 3 to 7 mΩ/cm resistivity from Siltronix (Archamps, France). The etched bulk

Si surface area is about 0.9 cm2. The etching solution was HF/H2O/ethanol in a 15/15/70 proportion, respectively, and the etching current density was 50 mA/cm2 in all cases. HF being an extremely hazardous material (e.g., see [23]), all precautions have been taken to ensure the safety of the persons involved in the porous samples preparation. 4EGI-1 order The Er doping was performed in constant current configuration with current densities in the 0.01 to 2.2 mA/cm2 range using a 0.11 M solution

of in EtOH. EIS measurements and Er doping processes were always performed with the same electrochemical cell used for the PSi formation. The Er solution used was also the same in both cases. The EIS measurements were made in the galvanostatic regime (GEIS) using a constant bias current in the 0.01 to 1 mA range, a frequency range from 100 kHz to 100 mHz, and an AC amplitude of 2 to 10 μA, depending on the bias current intensity. All electrochemical processes were performed using a PARSTAT 2273 potentiostat by Princeton Applied Research (Oak Ridge, TN, USA). A schematic of the cell used for the experiments can be found in [14]. Spatially resolved energy https://www.selleckchem.com/products/dinaciclib-sch727965.html dispersive spectroscopy (EDS) measurements for quantitative Er content determination were 4��8C carried out using a JEOL JED 2300 Si(Li) detector in a scanning electron microscope (SEM) JEOL JSM 6490-LA (JEOL Ltd., Akishima, Japan) equipped with a W thermionic electron source and working at an acceleration voltage of 15 kV. The fitting of the reflectivity spectra was performed using the SCOUT software from W. Theiss Hard- and Software (Aachen, Germany). Talazoparib solubility dmso results and discussion Optical characterization The presence of Er within the PSi pores induces

a modification of the optical response of the material that is correlated to the amount of Er present in the layers [14]. To gain information about the modifications of the PSi/Er doping process as a function of the doping current intensity, we performed a series of reflectivity measurements on samples where we transferred, using different current intensities, equal amounts of charge during the electrochemical process. We have then fitted the reflectivity spectra, using the SCOUT software, to obtain the variation of the optical thickness following the Er doping. Each sample has been measured before and after the doping process, so that the results are independent on small differences in the thickness from one sample to another.