Recoil implantation of alpha sources for thickness measurement of thin films

Abstract

A sequence of radioactive decays can be used to implant alpha-emitting sources in substrates for thickness measurements of films grown on them. Starting with 228Th, both direct recoil implantation of 224Ra and a two-stage recoil implantation of 212Pb were performed. The thickness of germanium layers grown on gallium arsenide was determined by measuring the energy loss of the alpha particles traversing them. The results were found to be consistent with those obtained by other methods. The special advantages of the present procedure are discussed.