Neon time-of-flight backscattering spectrometry for surface analysis

Abstract

Several time-of-flight backscattering spectrometry experiments using singly ionized neon for purposes of analyzing a bismuth coated silicon target were conducted. This work builds upon prior work, done with lighter ions, with the goal of comparing the observed system resolutions with those obtained previously in similar analyses. Discriminator thresholds, electronic start/stop logic, aperture sizes, target tilt and beam energies were varied and studied to determine their effect on system resolution. Depth resolutions below 10 A[], energy resolutions less than 1 keV and sensitivities of 10¹¹ (atoms/cm²)were attained. Comparison to prior research indicates the depth resolutions are significantly improved while energy resolutions are slightly improved. However, there does appear to be room to further improve upon these results. This work also indicates the presence of a previously unobserved and unexpected target tail feature on the analysis spectra. A possible cause for the tail feature is suggested and recommendations are given for further research to both improve the system resolution and to further analyze the tail feature.