Methods PSi was formed by electrochemical Captisol mw etching of 10 × 10 cm2 p-type mirror-polished Cz silicon wafers with boron doping level 1019 cm−3, under anodic bias and using an electrolyte of HF/ethanol mixture. A Teflon cell, with a platinum cathode and the silicon substrate as the anode, was used. PSi mono- and double-layer stacks were etched in galvanostatic mode at various current densities, as shown in Table 1. The porosity of the

various layers was determined by the gravimetric method, using a cross-sectional scanning electron microscopy (SEM) view to determine the layer thickness. Afterward, the samples were annealed in a commercial epitaxial reactor (ASM Epsilon 2000, Conquer Industries, Inc, Union City, CA, USA), a single-wafer atmospheric-pressure chemical vapor deposition system (APCVD), at 1,130°C in 1 atm of H2 ambient for various durations between 1 and 120 min. The reorganization rate of the samples was fully reproducible for the samples in the same batches, i.e., annealed at the same moment of time. However, this reproducibility is affected for samples from different batches,

probably due to the ageing of the epi-reactor. In this article, all samples shown on the same figure were loaded in the same batches, except for one figure that will be specified. A schematic representation of the Nepicastat ic50 temperature profile inside the reactor

is shown in Figure 2, where the solid line shows the typical temperature profile for PSi annealing. The dashed line shows the additional time of epitaxial growth, which was not performed in the present work in order to maximize the XRD signal from the PSi stacks. Lattice strain was estimated by X-ray diffraction through symmetric (004) reciprocal lattice point with high-resolution Omega-2theta scans, which were performed in Bede Metrix-L (Bede Scientific, Durham, England). The source was monochromatic CuKα1 radiation (λ = 1.54056 Å) collimated by a four-reflection Ge monochromator with a beam size of 1 cm. In addition, a Gaussian fitting for the PSi peak was performed to some XRD profiles. The surface roughness of the sintered PSi stacks was investigated by a stylus-based HRP measurement Dimethyl sulfoxide using a HRP-200 (distributed by KLA Tencor, Milpitas, CA, USA), with a resolution of 5 nm. The RMS roughness values given are the average of three measurement points. Two types of scans were used, firstly, over areas of 20 × 20 μm2 with 21 lines spaced of 1 μm and, secondly, an area of 100 × 100 μm2 with the same pitch. The PSi layer’s morphology was examined by SEM to determine the thickness of the PSi layers, to capture the evolution of the pillars in the HPL and to monitor the bigger pores at the top surface of the PSi seed layers.