A field-ion microscope study of ion-implantation in iridium I. philosophy and preliminary considerations

Abstract

The field-ion microscope has been used to investigate some of the processes occurring during ion-implantation, in particular, the fate of the implanted species. Attention is therefore paid to point defect contrast in field-ion images to establish the validity of counting such defects. The importance of bright spots is emphasized since they may represent the only type of contrast which could lead to unambiguous detection of isolated implanted atoms. Since self-interstitial atoms released from traps by the imaging process contribute to the bright spot concentration, consideration is given to the imaging mechanism and to means of distinguishing between bright spots caused by different defects. It is shown that, in the case of oxygen implants, such a distinction is possible, and further, that the implanted species is trapped, possibly as part of a ‘complex’. Control experiments to ensure that real effects are observed, and errors in defect counts are briefly mentioned and it is concluded that significant data can be extracted from field-ion micrographs provided care is taken in selecting a suitable implantation.