Depth distribution of implanted helium and other low-z elements in metal films using proton backscattering

Abstract

The depth profiles of helium implanted into copper foils have been observed experimentally by a proton backscattering technique. Carbon and oxygen on the front and rear surfaces of the foils have also been resolved. The mean depth of the helium implanted at 50, 100, and 150 keV is in agreement with projected range calculations, though the rms spread in the distributions is smaller than predicted. The shape of the profiles is the Gaussian form expected from single energy implants with no evidence of tails extending deep into the foils. Detection sensitivity is greater than 1 at.% for He in Cu under the experimental conditions investigated. The mean depth (peak) of the implanted helium distributions can be determined to within ± 100 Å.