Online monitoring of ion induced modifications by ERDA using a large area position-sensitive detector telescope

Heavy ion induced materials modifications, seen as composition or depth profile changes, can be measured in situ by ERDA (elastic recoil detection analysis). The necessity and importance of a large area position sensitive detector telescope, which combines high depth resolution and large detection efficiency, is pointed out for this technique by two examples. One is an ERDA experiment carried out during 243 MeV Au ion irradiation of a thin Fe film on Si. The dynamic measurement revealed changes in the depth profile of Fe and O due to ion induced oxygen absorption. A comparison is made of the present result with the result of a fictitious conventional detector telescope whose solid angle is considerably smaller. The other example is a blocking-ERDA experiment with a 165 MeV Ni beam on a Ge crystal where the damage was followed as a function of ion fluence. This work demonstrates the suitability of the experimental setup used for online monitoring of ion induced modifications. (C) 1998 Elsevier Science B.V. All rights reserved.