Diffusion of Ir into Si was investigated by annealing of front-side deposited floating-zone Si wafers at temperatures between 1000 and 1200 C. Concentrations-depth profiles were measured by means of neutron activation analysis in conjunction with mechanical sectioning. The observed deep penetrations and anomalous profile shapes point to a diffusion process involving both highly mobile interstitial Iri as diffusion vehicle and immobile substitutional Irs as dominating species. The experimental findings were best reproduced by making allowance for Iri-Irs exchanges that simultaneously take place via Si self-interstitials (kick-out mechanism) and Si vacancies (dissociative mechanism). As a unique property it was found that the Si:Ir system was subject to a gradual transition from a Iri-controlled diffusion mode at higher temperatures to a self-interstitial-controlled diffusion mode at lower temperatures.

Diffusion of Iridium in Silicon - Changeover from a Foreign-Atom-Limited to a Native-Defect-Controlled Transport Mode. S.Obeidi, N.A.Stolwijk: Physical Review B, 2001, 64[11], 113201 (4pp)