Applied Surface Science 43 (1989) 237-241 237 North-Holland EFFECTS ON THE IMPLANTED PROFILES OF POINT DEFECT FLUX DURING NITROGEN IMPLANTATION IN COPPER D.C. KOTHARI Istituto per la Ricerca Scientifica e Tecnologica, 1-38050 Povo, Trento, Italy and A. MIOTELLO Dipartimento di Fisica, Unitgt GNSM-CISM, 1-38050 Povo, Trento, Italy Received 30 May 1989; accepted for publication 20 June 1989 Coupled continuity equations for nitrogen atoms and vacancy fluxes are solved for known experimental conditions concerning the depth profiles of nitrogen implanted in copper at different energies and temperatures. It is observed that for implantations carried out at 200 ° C, nitrogen atoms possibly get trapped into vacancies during implantation and the vacancies tend to form clusters. The surface peak observed in depth profile data is shown to be due to Gibbsian segregation. The nitrogen diffusion coefficient is observed to be almost constant as temperature increases from -200 °C up to 200 o C. 1. Introduction Ion implantation is a well established process to introduce any element into any material, to a depth which is controlled by the ion energy and the stopping power of the substrate material. However, the depth control is lost if thermally activated radiation induced processes come into play. In such a situation, the depth profiles of implanted atoms can vary drastically from those predicted by the LSS theory [1]. The LSS theory takes into account the collisional effects which are non-thermal and which take place within a time period much less than a pico-second after the primary collisions. On the contrary the radiation induced effects are temperature dependent and take place during a time period of a pico-second to a milli-second after the primary collision. Radi- ation induced redistribution of atoms can take place due to preferential coupling between the point defect flux and the flux of implanted atoms. It is well known that during ion implantation, numerous point defects (vacancies and intersti- 0169-4332/89/$03.50 © Elsevier Science Publishers B.V. (North-Holland) tials) are produced. These defects migrate towards sinks such as the surface, grain boundaries, etc. The movement of the defects induces the trans- port of implanted atoms. Experimentally solute elements in irradiated alloys have been observed to migrate towards [2] or away [3] from the sink. There are various theories which relate the trans- port of solute atoms to the flux of vacancies [4] or interstitials [5]. However the lack of knowledge of various parameters used in the theories, makes quantitative prediction difficult. In such a case a numerical solution of the transport equations to fit experimental data can be used to obtain insight into the process. In the present work the numeri- cal approach is used for understanding the radia- tion induced effects on the nitrogen implanted copper system. 2. Theory In order to describe nitrogen relocation in copper during nitrogen implantation, both the bulk