Observation of Substitutional Fe in CEMS Measurements on Synthetic CVD Diamond

摘要

Conversion electron Moessbauer spectroscopy measurements have been made on a diamond sample synthesized by chemical vapour deposition. The sample was implanted with 70 keV ~(57)Fe to a dose of 5 x 10~(14) cm~(-2) and Moessbauer measurements were made on the as-implanted sample and after annealing at temperatures of 600 K, 950 K and 1470 K. The spectra at the lower temperatures were characterized by broad doublets, but the annealing at 1470 K resulted in dramatic decrease in the intensity of the doublet components, and the appearance of a strong single line with an isomer shift of δ = —0.90(5) mm/s and areal intensity of 30%, and a weaker line (5%) with δ = +0.07(4). Arguments are presented to attribute the single lines to substitutional and interstitial Fe, respectively. In contrast, identical measurements made on diamonds synthesized in the high temperature high pressure process showed little evidence of any strong single line component.