Materials characterisation using heavy ion elastic recoil time of flight spectrometry

Abstract

Materials characterisation by heavy ion elastic recoil time of flight spectrometry (HIERTOFS) at a forward recoil angle of 45° has been investigated using 40–110 MeV chlorine and iodine ions. Measurements are compared with a computer simulation code that evaluates the resolution components such as those due to straggling, multiple scattering, roughness and detector resolution both at the surface and at depth within the sample. The code also simulates elastic recoil time of flight spectra, which compare favourably with RBS analysis techniques. The ToF detector has a timing resolution of the order 300 ps, a mass resolution, for 30 MeV gallium recoils, of 4–5 amu and a depth resolution of 150 Å at the surface. The spectrometer to date has been used to characterise such materials as YBCO thin films, GaAs structures and implanted silicon samples.