HIGH-RESOLUTION ELASTIC RECOIL DEPTH PROFILING USING ALPHA-PARTICLE BEAMS - CERDA-TOF

An improved coincidence time-of-flight recoil spectrometer is described. The use of alpha-particles instead of heavy ions to eject the recoils has the advantages of larger depth range and smaller target damage. Multi-element analysis and element-selective depth profiling on thin and moderately thick targets are demonstrated. A surface depth resolution of 3 nm has been obtained for C-12 in carbon at a recoil angle phi of 30-degrees. Resolution down to 1 nm is predicted when further compensation of kinematic effects is realized; using very well defined beams it might be possible to obtain atomic layer resolution. Strategies to extend the present sensitivity of about 10(14) atoms/cm2 by one or two orders of magnitude are discussed.