Figure 1.

Scanning electron micrograph (a) and AFM gradient image (b) of patterned region on (001) Si substrate. The pit diameter was 100 nm while the depth ~70 nm. We choose the coordinate axes x and y to be parallel to the images edges, which are aligned to the [110] and directions, respectively

Bollani et al. Nanoscale Research Letters 2010 5:1917-1920   doi:10.1007/s11671-010-9773-0