Scaling laws in etched Si surfaces

Self-affine scaling behavior of etched crystalline Si surfaces has been investigated by atomic force microscope. Si surfaces were etched by a small drop (a few {μ}L) of NaOH solution. Percolation characteristics were observed at the initial stages of Si(100) chemical etching. Roughness exponent ({α}) values increase with etching time, from 0.6 to 0.8, and the {α} functional behavior with respect to the etching power agrees with the Kessler-Levine-Tu model. Anomalous scaling behavior was characterized for etched Si(111) surfaces. The local value of the roughness exponent is associated to the diffusional process of plateau growth. The global value of {α} is close to 0.4, a typical value for the Kardar-Parisi-Zang model, reflecting the highest growth rates on surfaces with higher slopes.