Surface topology using rutherford backscattering

Abstract

In order to investigate roughness, we have scattered protons in the vicinity of 400 keV off a variety of surfaces. The energy spectra were measured using surface barrier detectors as a function of incident and emergent angle. Spectra have been calculated theoretically, simulating the particle trajectories using both analytical and computer techniques. The analytical method has lead to rules connecting the spectral shape for smooth and rough surfaces. A statistical computer model has been used to investigate random roughness. It was found that there was a unique relationship between the energy spectrum and surface parameters. In order to confirm the predictions concerning surface oscillations, the spectra of protons scattered from an aluminized diffraction grating of 1200 lines per mm were observed. The profile of the grating was found using a scanning electron microscope. There was agreement between the calculated spectrum, based on the profile and the oscillations in the experimental backscattering spectrum. Experiments were performed on rough aluminum surface and the spectra were analyzed with the aid of the computer program based on the statistical model.