Research data for: Shaping the electric field: Overcoming geometric inhomogeneities in the electrochemical fabrication of mesoporous materials

Research data underlying the study of how the internal geometry of an electrochemical etching cell shapes the current distribution and hence the homogeneity of mesoporous silicon layers. Three PTFE cells differing in the height of the internal widening step (A: 4.75 mm, B: 8.0 mm, C: 25.0 mm) were compared, using an identical pulsed galvanostatic recipe on boron-doped Si(001) (0.01–0.02 Ω cm) in 2:3 HF(48 %)/ethanol.

Simulation - COMSOL Multiphysics models (6.4: fielddistribution_*.mph, 6.2: hyperelastic_seal_*.mph):
fielddistribution_*.mph are 2D axisymmetric primary-current-distribution models built from the CAD of each cell, including parametric sweeps of step height, seal overlap and an immersed insulating obstacle. hyperelastic_seal_*.mph are the solid-mechanics models of the compressed O-ring that supply the deformed seal profile used in the field models.
Model-to-cell assignment: V0 = cell B, V2 = cell A, V5p3 = cell C.

NIR - Spatially resolved reflectance area scans (HDF5):
Each file holds one 40 × 40 mm raster of 115 × 115 = 13 225 points at 0.35 mm pitch, recorded simultaneously by two Avantes AvaSpec spectrometers stored under their serial numbers: 2101075U1 (NIR, 512 px, 894–1692 nm) and 2012190U1 (UV/VIS, 2048 px, 176–1334 nm). The paper's analysis uses the NIR channel over 1150–1350 nm. Per scan: spectrum (raw counts), wavelength (in metres), position_x/position_y and their target values (mm), timestamp (Unix epoch, s) and a per-pixel saturated flag. Acquisition settings are stored as attributes on the scan_1 group.

Each sample was scanned twice per the spectroscopic liquid infiltration method: once in ambient air (*_cleaned / *_2xcleaned) and once infiltrated with ethanol (*_EtOH), to decouple layer thickness from porosity. Sample-to-cell mapping: A = 1851251014, B = 1841251008, C = 1831251008. 1741250707_pSi_(1)_reference&dark.h5 contains the dark spectrum used to dark-correct every area scan. Each scan was normalised by the spectrum of an unetched bulk-silicon point within the same scan (see README).