Comparison of electrochemical parameters regarding the over-etching at the porous region edges. In both cases, a 15-μm-pitch, 30-Ω cm n-type substrate was etched for 3 h into a HF (2.4 wt.%)-Triton X-100® (500 ppm) mixture. (a) The electrochemical etching was performed under 6-V bias (vs. CE) and 50-W backside illumination. (b) The macropores were etched under 3.5 V/CE under 140-W backside illumination.
Defforge et al. Nanoscale Research Letters 2012 7:344 doi:10.1186/1556-276X-7-344