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 dept h profile changes, can be measured in situ by ERDA (elastic recoil det ection analysis). The necessity and importance of a large area positio n sensitive detector telescope, which combines high depth resolution a nd large detection efficiency, is pointed out for this technique by tw o examples. One is an ERDA experiment carried out during 243 MeV Au io n irradiation of a thin Fe film on Si. The dynamic measurement reveale d changes in the depth profile of Fe and O due to ion induced oxygen a bsorption. A comparison is made of the present result with the result of a fictitious conventional detector telescope whose solid angle is c onsiderably smaller. The other example is a blocking-ERDA experiment w ith 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 modif ications. (C) 1998 Elsevier Science B.V. All rights reserved.