An in-depth study of metal assisted chemical etching (MACE) of p-type c-Si in HF/HO aqueous solutions using Pt nanoparticles as catalysts is presented. Combination of cyclic voltammetry, open circuit measurements, chronoamperometry, impedance spectroscopy, and 2D band bending modeling of the metal/semiconductor/electrolyte interfaces at the nanoscale and under different etching conditions allows gaining physical insights into this system. Additionally, in an attempt to mimic the etching conditions, the modeling has been performed with a positively biased nanoparticle buried in the Si substrate. Following these findings, the application of an external polarization during etching is introduced as a novel efficient approach for achieving straightforward control of the pore morphology by acting upon the band bending at the Si/electrolyte junction. In this way, nanostructures ranging from straight mesopores to cone-shaped macropores are obtained as the Si sample is biased from negative to positive potentials. Remarkably, macroscopic cone-shaped pores in the 1-5 μm size range with a high aspect ratio (L/W ∼ 1.6) are obtained by this method. This morphology leads to a reduction of the surface reflectance below 5% over the entire VIS-NIR domain, which outperforms macrostructures made by state of the art texturization techniques for Si solar cells.

In this paper we study the behavior of Internet traffic on the ASlevel topology and discuss its implications on interdomain traffic engineering. We rely on two notable interdomain traffic traces, the first is one month long and the other is one day long. This study shows that interdomain paths are stable for a large majority of the traffic from a routing viewpoint. We show that the aggregation of the traffic occurring on the AS-level graph is essentially limited to direct peers, with almost no aggregation occurring at larger AS hop distances. Furthermore, only part of the AS paths of the AS-level topology that see a lot of traffic are stable, when considering their presence among the largest AS paths on a hourly basis. Relying on the largest AS paths in traffic over a time window to capture the traffic over the next time interval discloses the important variability of the traffic seen by the largest AS paths in traffic. Interdomain traffic engineering is hence due to be difficult because of the limited traffic aggregation on the AS-level topology and the important topological variability of the traffic for a significant percentage of the total traffic.

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