Scanning electron micrographs of elliptical nanostructure on Si substrates. The spacings of the elliptical nanostructure were (a) 15 ± 1nm, (b) 18 ± 1nm, and (c) 22 ± 2nm. With the dwell time and etching time increasing, the spacing increased too. Bar = 500nm.
Gao et al. Nanoscale Research Letters 2012 7:399 doi:10.1186/1556-276X-7-399