  The effect of bias voltages on the statistical properties of rough surfaces
has been studied using atomic force microscopy technique and its stochastic
analysis. We have characterized the complexity of the height fluctuation of a
rough surface by the stochastic parameters such as roughness exponent, level
crossing, and drift and diffusion coefficients as a function of the applied
bias voltage. It is shown that these statistical as well as microstructural
parameters can also explain the macroscopic property of a surface. Furthermore,
the tip convolution effect on the stochastic parameters has been examined.
