Nanopillar length as a function of etching time and molar ratio. (a) The length of the nanopillars as a function of etching time for the highly doped Si in the λ3 solution and (b) the length of the nanopillars as a function of molar ratio λ for both highly doped Si (square symbols) and lightly doped Si (circular symbols) with a constant etching time of 10 min. Fully filled symbols indicate the length of the nanopillars, half-filled symbols indicate the total length of the pillars and the thickness of the nanoporous base layer, and unfilled symbols indicate the thickness of the nanoporous base layer in the absence of nanopillars. The inset in (b) is a magnified view of the position indicated by the arrow.
Wang et al. Nanoscale Research Letters 2013 8:42 doi:10.1186/1556-276X-8-42