NONDESTRUCTIVE STUDY OF THE ION-IMPLANTATION-AFFECTED ZONE (THE LONG-RANGE EFFECT) IN TITANIUM NITRIDE

The depth to which metal ion implantation can change the structure of titanium nitride coatings is studied using two techniques-positron ann ihilation spectroscopy (PAS) and glancing-angle X-ray diffraction (GA- XRD)-which are normally applied to the study of bulk materials. The PA S results indicate that the depth to which vacancies are found greatly exceeds the depth at which the implanted material resides. In additio n, the concentration of vacancies continues to increase with the dose of implanted ions. The GA-XRD data show that the implantation does not change the residual stress-it remains slightly tensile. Furthermore, there is an increase in the diffraction peak broadening, which is attr ibuted to an increase in the local strain distribution resulting from the generation of a dislocation network at depths of up to several ten ths of a micrometer below the implanted zone. The data support the vie w of a long-range effect, where metal ion implantation causes lattice defect generation within an implantation-affected zone (IAZ) to depths well beyond the implanted zone. The defective nature of the IAZ depen ds on the implanted dose and the acceleration voltage, as well as on t he nature of the ions implanted. In the present work, there is no resi dual stress in the samples, so this cannot induce the IAZ.