Studies of surface evolution and self-affine properties of germanium by off-normal Kr ion beam sputtering.

We present the surface evolution of the single crystal germanium substrates bombarded with 200 keV Kr ions at a constant fluence of 5.0 × 1017 ions/cm2 at various off-normal ion incident angles, viz. 40°, 50°, 60°, and 70°. The surface morphologies of the irradiated samples were obtained by scanning the surface of size 10 × 10 µm2, using Atomic Force Microscopy (AFM). The data acquisition and off-line analysis of AFM micro images were done by WSxM and Nanoscope software. The statistical surface data points were analysed by the Fractal method to obtain the surface parameters, and for comparative study, the roughness exponent was also obtained from the power spectral density method. The self-affine nature of the samples and the evolution of the ripple pattern are both clearly visible in the fractal correlation plots. [ABSTRACT FROM AUTHOR]